Objective To study the electrochemical behavior of Bi, Te and Se in sulfuric acid system, providing the theoretical reference for the electrodeposition process of n-type Bi2Te3-y Sey thermoelectric material. Methods The electrochemical reduction processes of elements Bi, Te and Se in sulfuric acid solution system as well as the codeposition among different elements were investigated by cyclic voltammogram measurements. Results In Bi solution system, the electrochemical reduction process of Bi3+ to elemental Bi could be divided in steps, and the free Bi Bismuth ions and complexed bismuth ions were reduced in sequence. In Te solution system, the adsorbed HTeO2 + and the fress HTeO2 + were reduced in sequence. In Se solution system, the H2SeO3 in the solution was also reduced to elemental Se through several steps. In the solution system containing elements Bi, Te and Se, the concentration of Bismuth ions and the difference between substrates had significant influences on the electrodeposition process. The BiTe-Se compound as cathode could stimulate the following electrodeposition. Conclusion In Bi-Te-Se ternary sulfuric acid electrolytes, a co-electrodepositing process of elements Se, Te, Bi could take place on the surface of the cathode through reduction to form Bi-Te-Se compound as n-type thermoelectric material.