The engine performance and exhaust emissions of biodiesel produced from peanut oil must be evaluated to assess its potential as an alternative diesel fuel. In this study, two diesel engines rated at 14.2 kW (small) and 60 kW (large) were operated on pure peanut oil biodiesel (PME) and its blends with a reference diesel (REFDIESEL). Results showed that comparable power and torque were delivered by both the small and large engines when ran on pure PME than on REFDIESEL while brake-specific fuel consumption (BSFC) was found to be higher in pure PME. Higher exhaust concentrations of nitrogen oxides (NO_x), carbon dioxide (CO₂) and total hydrocarbons (THC) and lower carbon monoxide (CO) emissions were observed in the small engine when using pure PME. Lower CO₂, CO and THC emissions were obtained when running the large engine with pure PME. Blends with low PME percentage showed insignificant changes in both engine performance and exhaust emissions as compared with the reference diesel. Comparison with soybean biodiesel indicates similar engine performance. Thus, blends of PME with diesel may be used as a supplemental fuel for steady-state non-road diesel engines to take advantage of the lubricity of biodiesel as well as contributing to the goal of lowering the dependence to petroleum diesel.