A biosensor for specific determination of hydrogen peroxide was developed by using homogenized artichoke (Cynara scolymus L.) tissue in combination with a dissolved oxygen probe and applied in determination of hydrogen peroxide in milk samples. Artichoke tissue, which has catalase activity, was immobilized with gelatine by means of glutaraldehyde and fixed on a pretreated teflon membrane. The electrode response was maximum when 0.05 M phosphate buffer was used at pH 7.0 and at 30degreesC. Upon addition of hydrogen peroxide, the electrode gives a linear response in a concentration range of 5.0-50x10(-5) M with a response time of 3 min. The method was also applied to the determination of hydrogen peroxide in milk samples.