In order to utilize the wildly grown plant seed oils as biodiesel, their fatty acid composition were used for empirical determination of saponification number, iodine value, and Cetane number. Among the oils from 23 plant species, saponification numbers, iodine values, and Cetane numbers varied from 181.98 to 294.30, 4.81 to 194.61, and 29.70 to 67.50, respectively. Biodiesel properties predicted from iodine values, Cetane numbers, and fatty acid composition of the respective oils, showed that five species, namely, Buchnania lanzan, Cleome viscosa, Manilkara hexendara, Merremia aegyptia, and Nyctanthes arbortristris, are most suitable for biodiesel, the FAMEs of which meet the biodiesel specifications of the USA, Germany, and European Standard Organization. Another five species, namely, Carthamus oxyacantha, Chrozophora plicata, Citrullus colocynthis, Cucurbita maxima, and Ipomoea pestigridis, meet the specification of the US Biodiesel Standard only. FAMEs of unsuitable oils may also be used as biodiesel if they are properly selected and mixed in proper ratio. Two unsuitable oils, Salvadora oleoides and Xanthium stumarium, for example, when mixed in 1:1 ratio, the resulting mixture meets the specifications of biodiesel standard. As B. lanzan, C. viscosa, M. hexendara, and C. colocynthis are found in abundance, have great potential for use as biodiesel.