Calf thymus DNA was modified on an electrically heated gold-wire microelectrode. Cyclic voltammetry was used to study the temperature behavior of Co(phen)(3)(3+/2+) at a bare gold electrode and a DNA modified gold microelectrode at different electrode temperatures. It is found that the temperature has a great influence on the interaction between Co(phen)(3)(3+/2+) and DNA. An increase of the peak current, a decrease of peak potential separation and a shift of the formal potential at a DNA modified gold electrode were observed with increase of the electrode temperature. This indicates that an increase in the electrode temperature cannot only improve the mass transfer, but also affect the nature of Co(phen)(3)(3+/2+) binding to DNA.