Electroless copper deposition using Co(II)-ethylenediamine (En) complexes as reducing agents was investigated in 0.4-1.2 M En solutions at 50 and 70 degreesC. There is a complicated dependence of the process rate on pH, En concentration and temperature. A copper deposition rate up to 6 mum h(-1) (50-70 degreesC) in relatively stable solutions (pH similar to 6) can be achieved. The stoichiometry of the Cu(II) reduction at pH 6-7 corresponds to the reaction: CuEn(2)(2+) + 2 CoEn(2)(2+) (Cu) under right arrow Cu + 2 CoEn(3)(3+) The correlation between the rate of the copper deposition on the catalytic surface and the concentration of the CoEn(2)(2+) complex species in the solution was found.