Abstract: This invention relates to electroless metal deposition and more specifically, to a process where a plating solution is brought to equilibrium and thereafter operated with the concentration of plating reactants and by-products maintained substantially constant. The plating solution treated in accordance with the invention is one having evaporative losses of at least one percent per plating cycle. Following the process, a plating solution can be operated indefinitely and yields a metal plate of uniform quality and predictable properties at any time during use of the solution. The invention avoids the known problems of by-product build-up and variable concentration of reactants typically associated with the use of such solutions.