Abstract Gear performance is significantly influenced by the interacting surface conditions; however, very few attempts have been made to understand the effect of mating surface condition. In this work, injection molded polypropylene gears were meshed with machined metal gears having different surface conditions. Bearing characteristics of the machined gears were obtained through non-contact profile meter and correlated with real area of contact and friction. Injected molded gears were run against metallic gears at various loads and net surface temperature due to the surface interaction was measured with non-contact temperature sensor and correlated with friction.