Characteristics of Candida rugosa lipase, which was entrapped in various alkyl-substituted organic silicates formed on Celite 545, have been investigated. The hybrid gel-entrapped lipase derived from an equimolar mixture of dimethyldimethoxysilane and tetramethoxysilane exhibited three times and ten times higher catalytic activity than deposited lipase on the same support at 35 o C and 75 o C, respectively. The enantioselectivity, defined as the ratio of the initial esterification rate of (-)-menthol to that of (+)-menthol, was increased with an increase in the chain length of the alkyl group and an increase in the number of the methyl group at 75 o C, whereas it remained virtually unchanged at 35 o C. The hydrophobic interaction between the lipase molecules and alkyl groups of the entrapping gel appeared to be a dominant factor for modification of the enzyme properties.