Abstract: Using two different formulations with isocyanate/polyol (NCO/OH) ratios of 1/2 and 1/1, rigid castor oil-based polyurethane foams (RCPUFs) were prepared by one-shot method. Foam reaction involved glycerolyzed castor oil containing varying concentrations (10-60 wt.%) of the modifier, and 80:20 mixture of 2,4- and 2,6- toluene diisocyanate (TDI) at room temperature, in presence of stannous octoate and dimethylaminoethanol (DMAE) catalysts, methylene chloride (physical blowing agent) and silicone oil (surfactant). Hydroxyl number range for the modified castor oil polyols (MCOPs) was 168 – 320mgKOH/g.