A new type of voltammetric sensor, Langmuir-Blodgett film of p-tert-butylthiacalix[4]arene modified glassy carbon electrode, was advanced and used for determining copper at trace levels by differential pulse stripping voltammetry. Calibration plot was found to be linear in the range of 2 x 10(-8) M to 5 x 10(-6) M; the detection limit was 2 x 10(-9) M. Possible recognition mechanism was also discussed. From determination of Copper in real samples (river, lake and tap water) it can be concluded that the method is rapid, sensitive in determining of copper and can be used in the analysis of natural water samples.