Biocatalytic synthesis of polyester of the type (AA-BB)(H) using a new diester, viz bis(2, 3 butane dione monoxime)alkane dioate by lipase catalysed transesterification with different primary diols has been studied. Weight average molecular weight(M(w)) of the polyester was analysed by gel permeation chromatography (GPC). Number average molecular weight (M(n)) of polyesters were measured by end group analysis and confirmed by vapour pressure osmometry (VPO). Solvent effect on the yield, M(n) and M(w) of the polymer was studied. The catalytic activity of different lipases are compared.