diff --git a/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.html b/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.html
index 2d992187f6..6f495984f5 100644
--- a/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.html
+++ b/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.html
@@ -35,7 +35,7 @@
           {{ 'gateway.rpc.withResponse' | translate }}
         </mat-slide-toggle>
         <mat-form-field *ngIf="isMQTTWithResponse.value">
-          <mat-label>{{ 'gateway.rpc.responseTopicExpression' | translate }}</mat-label>
+          <mat-label>{{ 'gateway.rpc.responseTopicExpression' | translate }}*</mat-label>
           <input matInput formControlName="responseTopicExpression"
                  placeholder="sensor/${deviceName}/response/${methodName}/${requestId}"/>
         </mat-form-field>
diff --git a/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.ts b/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.ts
index 2ea5964b84..cbb11fc059 100644
--- a/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.ts
+++ b/ui-ngx/src/app/modules/home/components/widget/lib/gateway/gateway-service-rpc-connector.component.ts
@@ -14,7 +14,7 @@
 /// limitations under the License.
 ///
 
-import { Component, EventEmitter, forwardRef, Input, OnInit, Output } from '@angular/core';
+import { Component, EventEmitter, forwardRef, Input, OnDestroy, OnInit, Output } from '@angular/core';
 import {
   ControlValueAccessor,
   FormArray,
@@ -22,6 +22,8 @@ import {
   FormControl,
   FormGroup,
   NG_VALUE_ACCESSOR,
+  UntypedFormControl,
+  ValidatorFn,
   Validators
 } from '@angular/forms';
 import {
@@ -53,6 +55,8 @@ import {
 } from '@shared/components/dialog/json-object-edit-dialog.component';
 import { jsonRequired } from '@shared/components/json-object-edit.component';
 import { deepClone } from '@core/utils';
+import { takeUntil, tap } from "rxjs/operators";
+import { Subject } from "rxjs";
 
 @Component({
   selector: 'tb-gateway-service-rpc-connector',
@@ -66,7 +70,7 @@ import { deepClone } from '@core/utils';
     }
   ]
 })
-export class GatewayServiceRPCConnectorComponent implements OnInit, ControlValueAccessor {
+export class GatewayServiceRPCConnectorComponent implements OnInit, OnDestroy, ControlValueAccessor {
 
   @Input()
   connectorType: ConnectorType;
@@ -105,6 +109,7 @@ export class GatewayServiceRPCConnectorComponent implements OnInit, ControlValue
 
   private propagateChange = (v: any) => {
   }
+  private destroy$ = new Subject<void>();
 
   constructor(private fb: FormBuilder,
               private dialog: MatDialog,) {
@@ -138,6 +143,17 @@ export class GatewayServiceRPCConnectorComponent implements OnInit, ControlValue
       }
     });
     this.isMQTTWithResponse = this.fb.control(false);
+    this.isMQTTWithResponse.valueChanges.pipe(
+      tap(() => {
+        this.commandForm.get('responseTopicExpression').updateValueAndValidity();
+      }),
+      takeUntil(this.destroy$),
+    ).subscribe();
+  }
+
+  ngOnDestroy(): void {
+    this.destroy$.next();
+    this.destroy$.complete();
   }
 
   connectorParamsFormGroupByType(type: ConnectorType): FormGroup {
@@ -148,7 +164,7 @@ export class GatewayServiceRPCConnectorComponent implements OnInit, ControlValue
         formGroup = this.fb.group({
           methodFilter: [null, [Validators.required, Validators.pattern(noLeadTrailSpacesRegex)]],
           requestTopicExpression: [null, [Validators.required, Validators.pattern(noLeadTrailSpacesRegex)]],
-          responseTopicExpression: [null, [Validators.pattern(noLeadTrailSpacesRegex)]],
+          responseTopicExpression: [null, [this.requiredOnWithResponse(), Validators.pattern(noLeadTrailSpacesRegex)]],
           responseTimeout: [null, [Validators.min(10), Validators.pattern(this.numbersOnlyPattern)]],
           valueExpression: [null, [Validators.required, Validators.pattern(noLeadTrailSpacesRegex)]],
         })
@@ -424,4 +440,16 @@ export class GatewayServiceRPCConnectorComponent implements OnInit, ControlValue
       this.commandForm.patchValue(value, {onlySelf: false});
     }
   }
+
+  private requiredOnWithResponse(): ValidatorFn {
+    return (control: UntypedFormControl) => {
+      const withResponse: boolean = this.isMQTTWithResponse?.value;
+
+      if (withResponse && !control.value) {
+        return { 'required': true };
+      }
+
+      return null;
+    };
+  }
 }