Highly active Pseudomonas aeruginosa lipase protein-coated microcrystals (PAL PCMC) have been prepared by immobilization of protein onto K2SO4 as excipient solid support carrier and n-propanol as precipitating solvent. Transmission electron micrographs confirmed the formation of PAL PCMC. These PCMC were found to be a catalytically more active and stable preparation for p-nitrophenyl palmitate hydrolysis in n-heptane, compared to free lipase. The V-max, K-m, and temperature optimum for PAL PCMC increased from 0.49 to 5.66 nmol min(-1) mg(-1), 589 to 679.8 mmol, and 40 degrees C to 45 degrees C, respectively. These were thermally more stable with 4.65, 2.56, and 1.24-fold improvement in half lives at 45 C, 55 C, and 60 C compared to free P. aeruginosa PseA lipase. Their catalytic efficiency was enhanced by tenfold over that of free enzyme. PAL PCMC offer a simple and effective technique for obtaining stable and efficient lipase preparation for biocatalysis in nonaqueous medium.