Rhizopus oryzae lipase prepared was immobilized in polystyrene electrospun fibers from a suspension of crude lipase powder in an N,N-dimethylformamide solution of polystyrene. The performance of the enzyme was enhanced by supplying water onto the resultant non-woven fabric. The electrospun fibers supplied with water by spraying showed 47-fold faster initial transesterification rate measured as conversion of (S)-glycidol to glycidyl n-butyrate with vinyl n-butyrate compared with a non-encapsulated crude lipase control. Before being moistened with water, the initial transesterification rate was slower than non-encapsulated lipase. The encapsulated and moistened lipase showed 77% of residual activity after 10 cycles of use. (C) 2009 Elsevier B.V. All rights reserved.