Consideration is given to the convection in an electrochemical system described, which enables Both opposing or aiding temperature and concentration gradients to be imposed. The flows have double-diffusive characteristics because of the large difference between the thermal and solutal diffusion rates. Complex flow patterns are observed as the parameters are varied. Under certain conditions the flow is found to become a fingering and multilayer structure in an annular enclosure. The dimensionless mass transfer rate Sh increases with increasing G(r,t) and fixed G(r, m), and Sh is higher in the aiding case than in the opposing case for the same G(r,t) and G(r,m) in the present experimental ranges.