The invention relates to a method for the treatment of work pieces with a palladium colloid solution by bringing the work pieces into contact with the colloid solution, palladium being recovered after the use of the colloid solution. This is achieved by separating palladium colloid particles from the colloid liquid by means of a molecular filter. With this method it is easy to continuously and largely completely separate palladium from the spent processing solutions without investing large amounts of chemicals, energy and time. The spent processing solution may especially be worked up after separation of the part of the solution containing palladium such that palladium can be recovered completely and be reused for further processing.