A new biosorption-based biosensor using Tetraselmis chuii microalgae was developed for the voltammetric measurement of copper(II). Biosensor was prepared by incorporating non-living biomass in carbon paste. T chuii incorporated in carbon paste electrodes (CPE) in weight percentages ranging from 2.5 to 20 accumulate copper(II) from solution through passive adsorption. Copper(II) was accumulated, at open circuit, on the algal biosensor and the voltammetric measurements were carried out by differential pulse cathodic stripping voltammetry. The biosensor performance was optimized with respect to the operating conditions. Under the optimal conditions, a detection limit of 4.6 x 10(-10) M was obtained with a good precision (R.S.D. = 3.4%, n = 6). The cathodic peak current was linear with concentration in the range of 5.0 x 10(-8)-1.0 X 10(-6) M (r=0.9981). The developed biosensor was also applied for the determination of copper(II) in real sample. Such an excellent performance of the algal biosensor toward copper(II), represents a very good alternative for developing other sensors. (c) 2007 Elsevier B.V. All rights reserved.