In this study, different mixtures of castor oil and linseed oil were converted into their corresponding biofuel throughout homogeneous catalytic reaction using sodium hydroxide as homogeneous catalyst in the presence of methyl alcohol under optimized condition. The mechanism of the transesterification reaction of the oils was proposed. The physical properties of the obtained biodiesels were determined according to ASTM fuel specification. The results showed that the gradual increase in the abundance of castor oil in the oil mixture from 10% to 90% decreases the most of properties of the obtained biofuels to meet the standard values. The study presented a good sight into the preparation of biodiesels from various types of mixed vegetable oils.