In modern pharmaceutical industry, N-acylation reactions are one of the most frequently used chem-ical reaction. The chemical synthesis of amide bonds has some limitations, such as by-products that are harmful to the environment, also affect the yield, and the need for either harsh reaction conditions or stoichiometric amounts of complex coupling agents. To overcome these problems, we have inves-tigated the use of some specific enzymes as biocatalysts for amidations. Biocatalysts have the ad-vantage of specificity and more benign reaction conditions. In this project Pseudomonas Stutzeri Li-pase (PSL) was used for the selective acylation of piperazines with esters as the acyl donors. A panel of amines and esters was screened to explore the substrate specificity of the enzyme.