Abstract: The invention relates to a method and an apparatus for forming bonding bumps on wafers (5) to be plated in an electroless process (not requiring an externally applied voltage). According to the method, the object to be plated is immersed in a vessel (2) containing a desired solution (10) of metal salts thermostatted at a desired temperature. According to the invention, the wafer (5) to be plated is fixed to a filler block (4) which has a volume essentially equal to the volume of the process vessel (2) to the end of reducing the required filling volume of the vessel (2), and said filler block (4) is moved in the vessel (2) for improving the mixing of the solution of metal salts contained therein.