diff --git a/flang/lib/Lower/IntrinsicCall.cpp b/flang/lib/Lower/IntrinsicCall.cpp
--- a/flang/lib/Lower/IntrinsicCall.cpp
+++ b/flang/lib/Lower/IntrinsicCall.cpp
@@ -542,6 +542,7 @@
   void genRandomInit(llvm::ArrayRef<fir::ExtendedValue>);
   void genRandomNumber(llvm::ArrayRef<fir::ExtendedValue>);
   void genRandomSeed(llvm::ArrayRef<fir::ExtendedValue>);
+  fir::ExtendedValue genReduce(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genRepeat(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   fir::ExtendedValue genReshape(mlir::Type, llvm::ArrayRef<fir::ExtendedValue>);
   mlir::Value genRRSpacing(mlir::Type resultType,
@@ -907,6 +908,15 @@
        {"put", asBox, handleDynamicOptional},
        {"get", asBox, handleDynamicOptional}}},
      /*isElemental=*/false},
+    {"reduce",
+     &I::genReduce,
+     {{{"array", asBox},
+       {"operation", asAddr},
+       {"dim", asValue},
+       {"mask", asBox, handleDynamicOptional},
+       {"identity", asValue},
+       {"ordered", asValue}}},
+     /*isElemental=*/false},
     {"repeat",
      &I::genRepeat,
      {{{"string", asAddr}, {"ncopies", asValue}}},
@@ -3686,6 +3696,13 @@
   Fortran::lower::genRandomSeed(builder, loc, size, put, get);
 }
 
+// REDUCE
+fir::ExtendedValue
+IntrinsicLibrary::genReduce(mlir::Type resultType,
+                            llvm::ArrayRef<fir::ExtendedValue> args) {
+  TODO(loc, "intrinsic: reduce");
+}
+
 // REPEAT
 fir::ExtendedValue
 IntrinsicLibrary::genRepeat(mlir::Type resultType,
diff --git a/flang/test/Lower/Intrinsics/Todo/reduce.f90 b/flang/test/Lower/Intrinsics/Todo/reduce.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Lower/Intrinsics/Todo/reduce.f90
@@ -0,0 +1,13 @@
+! RUN: %not_todo_cmd bbc -emit-fir %s -o -  2>&1 | FileCheck %s
+
+interface
+  pure function chfunc(a,b)
+    character(*),intent(in) :: a,b
+    character(3) :: chfunc
+  end function
+  end interface
+  character(3) x(5)
+  print*, reduce(x,chfunc)
+end program
+
+! CHECK: not yet implemented: intrinsic: reduce