A silica gel-based prolonged-release system for methanol was applied in biodiesel production catalyzed by lipase LipB68, instead of the traditional method of three-step addition of methanol. With the application of the prolonged-release system, the recycle times of the catalyst increased substantially from one-off usage to at least six cycles with no detectable decrease in activity, and the yield of biodiesel (94%) remained at a higher level compared with the yield of 92% with the previous method. The results showed the potential of this methanol addition method with little harm to the catalyst. (c) 2006 Society of Chemical Industry.