diff --git a/packages/page-rpc/src/Rpc/Selection.tsx b/packages/page-rpc/src/Rpc/Selection.tsx
index 0457a21bb5..631e4b385b 100644
--- a/packages/page-rpc/src/Rpc/Selection.tsx
+++ b/packages/page-rpc/src/Rpc/Selection.tsx
@@ -72,7 +72,7 @@ function Selection ({ queueRpc }: Props): React.ReactElement<Props> {
     (): void => queueRpc({
       rpc,
       values: values
-        .filter(({ value }) => !isNull(value))
+        .filter(({ value }, idx) => !rpc.params[idx].isOptional || !isNull(value))
         .map(({ value }): any => value)
     }),
     [queueRpc, rpc, values]
diff --git a/packages/react-params/src/Holder.tsx b/packages/react-params/src/Holder.tsx
index e378694780..1ebec55078 100644
--- a/packages/react-params/src/Holder.tsx
+++ b/packages/react-params/src/Holder.tsx
@@ -98,6 +98,10 @@ const StyledDiv = styled.div`
     text-align: right;
   }
 
+  .ui--Param-BTreeMap-buttons {
+    text-align: right;
+  }
+
   .ui--Param-composite {
     position: relative;
 
diff --git a/packages/react-params/src/Param/BTreeMap.tsx b/packages/react-params/src/Param/BTreeMap.tsx
new file mode 100644
index 0000000000..b551738889
--- /dev/null
+++ b/packages/react-params/src/Param/BTreeMap.tsx
@@ -0,0 +1,160 @@
+// Copyright 2017-2024 @polkadot/react-params authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import type { ParamDef, Props, RawParam } from '../types.js';
+
+import React, { useCallback, useEffect, useState } from 'react';
+
+import { Button } from '@polkadot/react-components';
+import { BTreeMap } from '@polkadot/types';
+import { isCodec, isUndefined } from '@polkadot/util';
+
+import Params from '../index.js';
+import getInitValue from '../initValue.js';
+import { useTranslation } from '../translate.js';
+import Base from './Base.js';
+import useParamDefs from './useParamDefs.js';
+
+function getParamType ([key, value]: ParamDef[]): ParamDef[] {
+  return [{
+    name: '(Key, Value)',
+    type: {
+      info: 17,
+      sub: [key.type, value.type],
+      type: `(${key.type.type}, ${value.type.type})`
+    }
+  }];
+}
+
+function getParam ([{ name, type }]: ParamDef[], index: number): ParamDef {
+  return {
+    name: `${index}: ${name || type.type}`,
+    type
+  };
+}
+
+export function getParams (keyValueParam: ParamDef[], prev: ParamDef[], max: number): ParamDef[] {
+  if (prev.length === max) {
+    return prev;
+  }
+
+  const params: ParamDef[] = [];
+
+  for (let index = 0; index < max; index++) {
+    params.push(getParam(keyValueParam, index));
+  }
+
+  return params;
+}
+
+export function getValues ({ isValid, value }: RawParam): RawParam[] {
+  return (isValid && isCodec(value) && value instanceof BTreeMap)
+    ? [...value.entries()].map(([key, value]: RawParam[]) => {
+      return {
+        isValid: true,
+        value: [{ isValid: true, value: key }, { isValid: true, value }]
+      };
+    })
+    : [];
+}
+
+function BTreeMapParam ({ className = '', defaultValue, isDisabled = false, label, onChange, overrides, registry, type, withLabel }: Props): React.ReactElement<Props> | null {
+  const { t } = useTranslation();
+  const keyValueParam = getParamType(useParamDefs(registry, type));
+  const [values, setValues] = useState<RawParam[]>(() => getValues(defaultValue));
+  const [count, setCount] = useState(() => values.length);
+  const [params, setParams] = useState<ParamDef[]>(() => getParams(keyValueParam, [], count));
+
+  // build up the list of parameters we are using
+  useEffect((): void => {
+    keyValueParam.length &&
+      setParams((prev) =>
+        getParams(keyValueParam, prev, isDisabled ? values.length : count)
+      );
+  }, [count, values, isDisabled, keyValueParam]);
+
+  // when !isDisable, generating an input list based on count
+  useEffect((): void => {
+    !isDisabled && keyValueParam.length &&
+      setValues((values): RawParam[] => {
+        if (values.length === count) {
+          return values;
+        }
+
+        while (values.length < count) {
+          const value = getInitValue(registry, keyValueParam[0].type);
+
+          values.push({ isValid: !isUndefined(value), value });
+        }
+
+        return values.slice(0, count);
+      });
+  }, [count, defaultValue, keyValueParam, isDisabled, registry]);
+
+  // when our values has changed, alert upstream
+  useEffect((): void => {
+    const output = new Map();
+    let isValid = true;
+
+    for (const entry of values) {
+      const [key, value] = entry.value as RawParam[];
+
+      if (output.has(key)) {
+        isValid = false;
+        console.error('BTreeMap: Duplicate key ', key);
+      }
+
+      output.set(key, value);
+      isValid = isValid && entry.isValid;
+    }
+
+    onChange && onChange({
+      isValid,
+      value: output
+    });
+  }, [values, onChange]);
+
+  const _rowAdd = useCallback(
+    (): void => setCount((count) => count + 1),
+    []
+  );
+  const _rowRemove = useCallback(
+    (): void => setCount((count) => count - 1),
+    []
+  );
+
+  return (
+    <Base
+      className={className}
+      isOuter
+      label={label}
+      withLabel={withLabel}
+    >
+      {!isDisabled && (
+        <div className='ui--Param-BTreeMap-buttons'>
+          <Button
+            icon='plus'
+            label={t('Add item')}
+            onClick={_rowAdd}
+          />
+          <Button
+            icon='minus'
+            isDisabled={values.length === 0}
+            label={t('Remove item')}
+            onClick={_rowRemove}
+          />
+        </div>
+      )}
+      <Params
+        isDisabled={isDisabled}
+        onChange={setValues}
+        overrides={overrides}
+        params={params}
+        registry={registry}
+        values={values}
+      />
+    </Base>
+  );
+}
+
+export default React.memo(BTreeMapParam);
diff --git a/packages/react-params/src/Param/Vector.tsx b/packages/react-params/src/Param/Vector.tsx
index 5dc30a9824..07658b83f0 100644
--- a/packages/react-params/src/Param/Vector.tsx
+++ b/packages/react-params/src/Param/Vector.tsx
@@ -22,8 +22,7 @@ function getParam ([{ name, type }]: ParamDef[], index: number): ParamDef {
 }
 
 export function getParams (inputParams: ParamDef[], prev: ParamDef[], max: number): ParamDef[] {
-  // HACK: I don't know why `max` changes to `undefined`.
-  if (prev.length === max || isUndefined(max)) {
+  if (prev.length === max) {
     return prev;
   }
 
@@ -61,9 +60,9 @@ function Vector ({ className = '', defaultValue, isDisabled = false, label, onCh
   useEffect((): void => {
     inputParams.length &&
       setParams((prev) =>
-        getParams(inputParams, prev, isDisabled ? (defaultValue.value as RawParam[] || []).length : count)
+        getParams(inputParams, prev, isDisabled ? values.length : count)
       );
-  }, [count, defaultValue, isDisabled, inputParams]);
+  }, [count, values, isDisabled, inputParams]);
 
   // when !isDisable, generating an input list based on count
   useEffect((): void => {
diff --git a/packages/react-params/src/Param/findComponent.ts b/packages/react-params/src/Param/findComponent.ts
index 2ee2ad1d2b..f569dce528 100644
--- a/packages/react-params/src/Param/findComponent.ts
+++ b/packages/react-params/src/Param/findComponent.ts
@@ -15,6 +15,7 @@ import Balance from './Balance.js';
 import AccountId20 from './BasicAccountId20.js';
 import AccountId32 from './BasicAccountId32.js';
 import Bool from './Bool.js';
+import BTreeMap from './BTreeMap.js';
 import Bytes from './Bytes.js';
 import Call from './Call.js';
 import Cid from './Cid.js';
@@ -76,6 +77,7 @@ const componentDef: TypeToComponent[] = [
   { c: Text, t: ['String', 'Text'] },
   { c: Struct, t: ['Struct'] },
   { c: Tuple, t: ['Tuple'] },
+  { c: BTreeMap, t: ['BTreeMap'] },
   { c: Vector, t: ['Vec', 'BTreeSet'] },
   { c: VectorFixed, t: ['VecFixed'] },
   { c: Vote, t: ['Vote'] },
@@ -126,6 +128,9 @@ function fromDef ({ displayName, info, lookupName, sub, type }: TypeDef): string
     case TypeDefInfo.BTreeSet:
       return 'BTreeSet';
 
+    case TypeDefInfo.BTreeMap:
+      return 'BTreeMap';
+
     case TypeDefInfo.Tuple:
       return components[type] === Account
         ? type