The electroconvective heat transfer coefficient (EHTC) from experiments on colloidal suspension (rod-like akageneite particle (RLAP) (beta-FeOOH) in distilled water) in a cylindrical enclosure is studied as a function of time, electric field, frequency, colloidal charge, concentration and orientation. The EHTC is strongly influenced by the charge and concentration of the colloidal particles. The EHTC data has been correlated by dimensional analysis. The data have been compared with the predicted correlations and are well correlated over the range of the Rayleigh number from 10(8) to 4.5 x 10(8). An empirical correlation relation has been proposed to evaluate the efficiency of convection (EOC) and the results for de and ac fields are presented.