The purpose of this study was to investigate the potential ability of carrageenan (kappa-, iota-, lambda-) and chitosan to form a controlled-release system for glucose oxidase (GOD). GOD was encapsulated in chitosan/carrageenan complexes at charge ratios (+/-) of 3 and 5 in mildly acidic solution. The encapsulation efficiency and activity of the loaded GOD were investigated. Among the different complexes prepared, chitosan/kappa-carrageenan complex showed high encapsulation efficiencies of 79% and 62.5% at charge ratios of 3 and 5, respectively. The order of encapsulation efficiency decreases toward chitosan/lambda-carrageenan complex (kappa > iota > lambda). After treatment with chitosanase and pepsin solutions, the activity of encapsulated glucose oxidase (GOD) was preserved for all complexes. The chitosan/kappa-carrageenan complex was able to preserve 80.2% of GOD activity in pH 1.2 solution, 73.3% in chitosanase solution and 66.4% in pepsin solution. Controlled release of GOD was observed when the complexes were treated with different physiological and enzyme solutions: the complex of chitosan/kappa-carrageenan had the lowest release rate of GOD. The simple preparation of chitosan/carrageenan complexes and their ability to protect protein integrity under acidic conditions make them a promising drug delivery system for the oral administration of peptides and proteins. (C) 2009 Elsevier Ltd. All rights reserved.