The catalytic performance of Ir/TiO2 reduced at low (573 K, LTR) and high temperature (773 K, HTR) was studied in the methylcyclopentane (MCP) reaction at atmospheric pressure in a flow system. Ir/Al2O3 was used as the reference catalyst. Catalysts were prepared by deposition-precipitation with urea and characterized by ICP, H-2-TPR, HAADF-STEM, Cs-STEM, and DRIFTS. For LTR samples, the activity follows the order Ir/TiO2 > Ir/Al2O3, and at low conversion and temperature, ring opening (RO) of MCP is selective (2MP/3MP = 2.7; n-H/3MP = 0.05) with S-RO = 100%. As the reaction temperature increased, C-1-C-5 products appeared but Ir/TiO2 was still more selective to RO products than Ir/Al2O3. Ir/TiO2 HTR was significantly less active, with S-RO = 100% and a product distribution approaching a nonselective behavior with n-H/3MP = 1. This was not observed in the case of Ir/Al2O3 HTR The structure of Ir/TiO2 HTR included nanoparticles, clusters of few atoms, and isolated iridium atoms. The results were analyzed in light of the metal-support interaction (SMSI) effect.