That barley and malt contain a range of esterases has long been known, and taken advantage of in terms of electrophoretic typing of varieties. However very little is known about the nature and role of the individual enzymes. Some of them are undoubtedly lipases, but other such enzymes in barley and malt may serve to sever acetyl- and feruloyl-bonds that might have a structural function in cell walls. Using electrophoresis as an analytical vehicle, we have investigated the distribution of esterases in the various tissues of barley and malt, and have assessed their relative heat tolerance, substrate specificity and inhibitor susceptibility. In this way we were able to identify which of these enzymes are likely to play a role in mashing. The most significant of these enzymes have been partially purified and investigated further.