For the purpose of fabricating a new glucose sensor, we demonstrate immobilization of glucose oxidase (GOx) in the organic-inorganic hybrid Langmuir-Blodgett (LB) films that consist of octadecyltrimethylammonium and Prussian blue (PB) nano-size clusters. In this report, the structural and the electrochemical properties are described. Transmission electron microscopy revealed that the size of PB clusters in the hybrid LB films was approximately 10 nm-20 nm and they formed a "knit-like" organization to give rise a stable nature to the film. A comparative study between before and after the GOx immobilization implies that GOx molecules are adsorbed into the specific site of the LB films where PB clusters do not exist. The GOx immobilized LB films showed a linear response of current density depending on the glucose concentration under a low potential range (0.0 V vs. Ag/AgCl). The fact indicates that the adsorbed nano-size PB clusters work well as an electrocatalyst for the reduction of hydrogen peroxide produced by enzymatic reaction of GOx. These experimental results suggest that the present LB films are applicable to glucose sensing devices. (c) 2007 Elsevier B.V. All rights reserved.