diff --git a/app/tasks/maintenance/populate_rnf_json_value_task.rb b/app/tasks/maintenance/populate_rnf_json_value_task.rb
new file mode 100644
index 000000000..50bf87a81
--- /dev/null
+++ b/app/tasks/maintenance/populate_rnf_json_value_task.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Maintenance
+  class PopulateRNFJSONValueTask < MaintenanceTasks::Task
+    include Dry::Monads[:result]
+
+    def collection
+      Champs::RNFChamp.where(value_json: nil)
+      # Collection to be iterated over
+      # Must be Active Record Relation or Array
+    end
+
+    def process(champ)
+      result = champ.fetch_external_data
+      case result
+      in Success(data)
+        begin
+          champ.update_with_external_data!(data:)
+        rescue ActiveRecord::RecordInvalid
+          # some champ might have dossier nil
+        end
+      else
+        # not found
+      end
+    end
+
+    def count
+      # not really interested in counting because it raises PG Statement timeout
+    end
+  end
+end
diff --git a/spec/models/champ_spec.rb b/spec/models/champ_spec.rb
index 22f64c5e7..4ea63a544 100644
--- a/spec/models/champ_spec.rb
+++ b/spec/models/champ_spec.rb
@@ -576,7 +576,7 @@ describe Champ do
     end
 
     context "fetch_external_data_later" do
-      let(:data) { { data: { address: { city: "some external data" } } }.with_indifferent_access }
+      let(:data) { { address: { city: "some external data" } }.with_indifferent_access }
 
       it "fill data from external source" do
         expect_any_instance_of(Champs::RNFChamp).to receive(:fetch_external_data) { data }
diff --git a/spec/tasks/maintenance/populate_rnf_json_value_task_spec.rb b/spec/tasks/maintenance/populate_rnf_json_value_task_spec.rb
new file mode 100644
index 000000000..d3e739ab3
--- /dev/null
+++ b/spec/tasks/maintenance/populate_rnf_json_value_task_spec.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+module Maintenance
+  RSpec.describe PopulateRNFJSONValueTask do
+    describe "#process" do
+      include Dry::Monads[:result]
+      let(:procedure) { create(:procedure, types_de_champ_public: [{ type: :rnf }]) }
+      let(:dossier) { create(:dossier, :with_populated_champs, procedure:) }
+      let(:element) { dossier.champs.first }
+      let(:data) do
+        {
+          id: 3,
+          rnfId: '075-FDD-00003-01',
+          type: 'FDD',
+          department: '75',
+          title: 'Fondation SFR',
+          dissolvedAt: nil,
+          phone: '+33185060000',
+          email: 'fondation@sfr.fr',
+          addressId: 3,
+          createdAt: "2023-09-07T13:26:10.358Z",
+          updatedAt: "2023-09-07T13:26:10.358Z",
+          address: {
+            id: 3,
+            createdAt: "2023-09-07T13:26:10.358Z",
+            updatedAt: "2023-09-07T13:26:10.358Z",
+            label: "16 Rue du Général de Boissieu 75015 Paris",
+            type: "housenumber",
+            streetAddress: "16 Rue du Général de Boissieu",
+            streetNumber: "16",
+            streetName: "Rue du Général de Boissieu",
+            postalCode: "75015",
+            cityName: "Paris",
+            cityCode: "75115",
+            departmentName: "Paris",
+            departmentCode: "75",
+            regionName: "Île-de-France",
+            regionCode: "11"
+          },
+          status: nil,
+          persons: []
+        }
+      end
+
+      subject(:process) { described_class.process(element) }
+
+      before do
+        allow_any_instance_of(Champs::RNFChamp).to receive(:fetch_external_data).and_return(Success(data))
+      end
+
+      it 'updates value_json' do
+        expect { subject }.to change { element.reload.value_json }
+          .from(nil)
+          .to({
+            "street_number" => "16",
+            "street_name" => "Rue du Général de Boissieu",
+            "street_address" => "16 Rue du Général de Boissieu",
+            "postal_code" => "75015",
+            "city_name" => "Paris 15e Arrondissement",
+            "city_code" => "75115",
+            "departement_code" => "75",
+            "departement_name" => "Paris",
+            "region_code" => "11",
+            "region_name" => "Île-de-France"
+          })
+      end
+    end
+  end
+end