The purpose of present study is to investigate laminar fully developed flow in a horizontal rectangular channel with the tandem cylinder sources under different Re and source positions. The boundaries in this experiment include four cases: (a) the former cylinder is cathode and the latter cylinder is anode; (b) the former cylinder is anode and the latter is cathode; (c) the upper plate is cathode and two cylinders are anode; and (d) the two cylinders are cathode and upper plate is anode. The influence of the mass transfer rate and the boundary types between the sources have also been investigated. An experimental study of mixed convection with CuSO4 + H2SO4 + H2O Solution in a horizontal channel was performed. The shadowgraph technique was used to visualize the flow and to determine the nature and effect of solutal driven secondary flows in a horizontal channel with the tandem cylinder sources inside. The ranges of the parameters studied in the present work are Pr = 5-7, Ar = 1, Sc = 1700-2400, Re = 50-200, Gr(m) 1. 75 x 10(5) (Re-d = 7.25-29, Grl*(m) = 6833.6), d/H = 0. 145.