The invention relates to a process for making esters, in particular biodiesel, using heterogeneous catalysts. The invention provides a process for making biodiesel, in particular FAME, which process is versatile and robust. The process of the invention can be carried out continuously, in particular in a fixed bed reactor or a slurry reactor and may be operated in a continuous fashion. In accordance with the invention, the transesterification reaction of triglycerides is carried out using a heterogeneous catalyst that comprises a Group 4 silicate and less than 3 wt. % Na in the presence of at least one acid compound.