Manganese (II) oxide (MnO) and titanium (II) oxide (TiO) solid catalysts were found to be robust catalysts for both the transesterification of triglycerides and esterification of free fatty acids. These metal oxides were shown to exhibit long life with little loss of activity. The ability to esterify free fatty acids (FFA) and handle high levels of water illustrates the potential of these catalysts to produce biodiesel from low quality feedstocks without the pretreatment operations required with the traditional process. Some soaps were produced in the presence of free fatty acids, but soaps were within tolerable levels and formed at concentrations that were orders of magnitude lower than the traditional process. This results in significant reductions in product washing. By utilizing a 2-stage process, high quality fuel (meeting ASTM specifications) and glycerol were produced. (C) 2011 Elsevier Ltd. All rights reserved.