A method of manufacturing electronic devices, in particular, but not exclusively, semiconductor devices, and apparatus for carrying out such a method, in which method wafers 1, which are provided at a surface 2 with a material 3 to be removed, are subjected, while being divided into successive batches, to a wet treatment in a bath 4 containing a solution 5 of an active component in a solvent. The successive batches of wafers 1 are immersed in the solution 5 at first time intervals during the wet treatment of the successive batches, which first time intervals each consist of a processing period during which the material 3 is removed from the surface 2 of the wafers 1, thereby forming ionic components, and a waiting period following the removal of the wafers 1 from the bath 4 at the end of the processing period. During the wet treatment of the successive batches the conductivity of the solution 5 is monitored, which monitored conductivity is brought to approximately a desired conductivity at second time intervals during the wet treatment of the successive batches by adding the active component or the solvent, or both, to the solution 5 inside the bath 4. In order to improve the process stability of the wet treatment of the successive batches of wafers 1 in the solution 5 of the active component in the solvent and to lengthen the lifetime of the bath 4 containing the solution 5, the desired conductivity is changed at third time intervals during the wet treatment of the successive batches with a value, which value is determined at each one of the third time intervals on the basis of the amount of the material removed during the latest completed one of the third time intervals.