Polyurethanes (PUs) are versatile polymers obtained by step growth polymerization between diisocyanate or polyisocyanate, and hydroxyl terminated oligomer (polyol) with at least two reactive hydrogen atoms. In this study, soy-based PU foams were prepared using different surfactants while keeping other ingredients such as polyol, isocyanate, and catalyst constant. The prepared samples were tested for mechanical and thermal properties to see the effect that surfactants impart upon these properties. The morphology of the foam samples was observed using scanning electron microscopy. Significant differences were observed in the cellular structure, thermal and mechanical properties of the foam samples. The cellular size of the foams was correlated with the mechanical and thermal properties. It was found that surfactants which reduced the viscosity of the polyol mixture to the greatest extent, produced smaller cell foams which exhibited the highest mechanical strength and thermal insulation.