Among the options explored for alternative energy sources, bio-diesel is one of the attractive alternatives. This paper discusses about the various production processes, few of which are applied at industrial level, to produce basically FAME (later can be utilized as bio-diesel after purification) and will be termed as bio-diesel in this paper. Transesterification of vegetable oils/animal fats and extraction from algae are the leading processes for bio-diesel production on large scale. This paper reviews briefly the literature on transesterification reaction using homogeneous, heterogeneous and enzyme catalysts. It is also reviewed the ultrasound, microwave and supercritical alcohol techniques and algae based bio-diesel. (C) 2011 Elsevier Ltd. All rights reserved.