The objective of this work is to investigate the addition of misfit elements in both size and mass on the evolution of irradiated microstructure in 316 SS. Alloys were modified by the addition of Pt and Hf to suppress the radiation damage. Pt and Hf were added as a lattice perturbation to catalyze defect recombination within the early stage of cascade formation and defect migration. Irradiations were conducted with 5 MeV Ni-ions at 500 °C to doses up to 50 dpa or with 3.2 MeV protons at 400 °C. Microstructures were characterized using transmission electron microscopy. While no beneficial effect was seen for Pt addition, Hf appears to effectively alter the microstructural response to irradiation.