Electroless deposition of cobalt using hydrazine as a reducing agent was investigated The rate of deposition increased with an increase in pH, temperature, and N2H4 concentration. Dependence of the rate of deposition on Co(II) concentration was found to pass through a maximum. Deposition of smooth and shiny Co deposits from the investigated solutions is possible within a relatively small range of pH (12.1 to 12.6). A further pH increase leads to an increase in the rate of deposition and formation of dendritic Co powder. Mechanistic aspects of Ca deposition using hydrazine as a reducing agent have also been discussed.