Silica xerogel was modified with an ionic silsesquioxane containing the cationic 1,4-diazoniabicyclo[2.2.2]octane bridged group and it was used as matrix for immobilization of copper tetrasulfonated phthalocyanine, resulting in Si/Db/CuTsPc material. This material was characterized by ultraviolet-visible and infrared spectroscopy, elemental and thermogravimetric analyses, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. The Si/Db/CuTsPc material was used to develop a carbon paste electrode for dopamine determination. The electrochemical behavior of dopamine was evaluated by cyclic voltammetry and chronoamperometry. The optimal experimental conditions were determined (pH = 4.5 and oxygen atmosphere) using a 0.1 mol L−1 phosphate buffer solution. The carbon paste electrode modified with the Si/Db/CuTsPc material shows a linear response for current intensity with the dopamine concentration in the range of 0.010 to 0.107 mmol L−1. The detection limit was 0.42 μmol L−1, and the sensitivity was 7.15 μA (mmol L−1)−1, making the system promising to be applied as electrochemical sensor for dopamine.