A new biosensor for the voltammetric detection of hydrogen peroxide was developed based on immobilization of catalase on a clinoptilolite modified carbon paste electrode using bovine serum albumin and glutaraldehyde. The biosensor response was evaluated according to electrode composition, reaction time, solution pH and temperature. The voltammetric signals were linearly in proportion to H(2)O(2) concentration in the range 5.0 x 10(-6) - 1.0 x 10(-3) M with a correlation coefficient of 0.9975. The detection limit is 8.0 x 10(-7) M and the relative standard deviation for 4.0 x 10(-4) M hydrogen peroxide was 1.83% (n = 6). The biosensor exhibited high sensitivity, and it was determined that it could be used for more than 2 months. In addition, the biosensor was successfully applied for the determination of hydrogen peroxide in milk samples.