Neutronic analysis on irradiation of the LEU electroplating target in the RSG-GAS reactor for production of 99 Mo radionuclide. RSG-GAS reactor is a research reactor operated for radioisotope production, neutron activation analysis, research material testing, industry demand, R & D institutions and universities. The irradiation of the LEU target on the reactor core to produce 99 Mo radioisotope is one of the routine activities of RSG-GAS reactor operation. The target insertion in the core will change the neutronic characteristic of the core so it can exceed the safety limits of reactor operation. The neutronic parameters due to the insertion of the LEU electroplating target into the reactor core irradiation facility is analyzed in this paper. The neutronic parameters for optimizing the LEU electroplating irradiated target are important for the safety of the reactor operation. Neutronic parameter calculations were performed using WIMS/D5 and Batan-3DIFF codes routinely used for RSG-GAS core calculations. Based on calculations irradiating the LEU electroplating target in a CIP irradiation position of 36 g causes a reactivity change of 597.724 pcm and a maximum radial power peaking factor of 1.3078. The values are within the limits permitted for the safety of the reactor operation i.e. the maximum reactivity change and radial power peaking factor of 2000 pcm and 1.4, respectively.