Abstractα‐Chymotrypsin immobilized on natural and inexpensive supports such as diatomaceous earth was used as catalyst for Z‐Tyr‐Arg‐NH2 (Z‐kyotorphin amide) synthesis. In order to obtain the optimal reaction conditions, a 22 factorial experimental design was used. The factors considered were cosolvent (dimethylformamide) concentration and temperature; optimal product yield was achieved at 40% (v/v) dimethylformamide and 25°C. A sequential kinetic model was considered which generally gave good agreement between experimental and theoretical data for continuous synthesis of Z‐kyotorphin amide in a packed‐bed immobilized reactor system. The activation energy for the synthesis was determined to be 48.0 ± 2.3 kJ mol−1.