The study of enzymes and their catalytic actions has become an important aspect of modern "biochemistry. Enzymes play an important part in the metabolism of living organisms because they catalyze most metabolic reactions. The absence or the loss of activity of a particular enzyme in the human metabolic cycle may cause serious disabilities such as in mental or physical development. The stereospecificity of o(-chymotrypsin catalysed hydrolysis of specific ester substrates has been investigated in this work. 4 series of diastereoisomeric phenylalanine (±) alkyl esters have been prepared and characterized by gas chromatography and mass spectrometry. highly sensitive gas chromatographic technique v/as developed to follow the course of the'enzyme hydrolysis quantitatively. Various methods of extracting significant informstiDn from the kinetic data were investigated and evaluated. The data obtained indicate that the structure and chirality of the alcohol moieties affect both the catalytic and binding constants of the substrates. The greatest difference between enantiomeric alcohol moieties are observed with esters derived from sterically crowded secondary alcohols. For racemic esters of the latter type, the stereospecificity of the alcohol site is such, that some resolution of racemic esters can be achieved viaiA~chymotrypsin catalysed hydrolysis on a preparative scale.