In this approach, flower-like cobalt with a hierarchical structure was applied as modifier for voltammetric determination of chlorpheniramine, which is an antihistaminic drug. The flower-like cobalt nanostructures were synthesized by using a simple chemical method. They have been characterized by using scanning electron microscopy and cyclic voltammetry. The carbon paste electrode modified with cobalt nanostructures shows an excellent electrocatalytic activity and sensitivity toward chlorpheniramine due to its unique properties such as high specific surface area and large pore volume. Potential sweep rate and pH effects on the response of the electrode for the oxidation of chlorpheniramine were investigated Differential pulse voltammetry has been applied for quantitative determination of chlorpheniramine. A dynamic linear range was obtained in the range of 1.0 x 10(-7)-1.0 x 10(-5) mol L-1, and the detection limit was estimated to be 8.0 x 10(-8) mol L-1.