This research focuses on the use of biodiesel as an additive in diesohol preparation. Three types of biodiesel-methyl, ethyl, and butyl esters-were prepared from palm oil through transesterification Using a conventional base catalyst. Ethanol is generally used to blend in diesohol; however, butanol is another alcohol which has higher solubility in diesel than ethanol and it can improve the fuel properties of the blends. Therefore, a comparative study of phase stability, the dependence of solubility on temperature (10, 20, and 30 degrees C), and an evaluation of some basic fuel properties according to the ASTM of diesel-biodiesel-ethanol and diesel-biodiesel-butanol three-component systems at different component concentrations was done. We found that the use of butanol in diesohol could solve the problem of fuel instability at low temperatures because of its higher solubility in diesel fuel. In addition, the fuel properties results indicated that blends containing butanol have properties closer to diesel than those of blends containing ethanol. (C) 2009 Elsevier Ltd. All rights reserved.