A neutron-activation method has been developed for the determination of the active constituents and contaminants in hydrogenation catalysts. The active constituents of palladium and nickel catalysts (Pd and Ni) and Zn and Co contaminants present in small amount were determined by a direct instrumental method. A NaI(Tl) scintillator and a Ge(Li) semiconductor connected to a multichannel analyser were used for the measurements. A computer was used to evaluate the gamma-spectra. Contaminants present in small amount were also determined by means of a radiochemical separation method based on heterogeneous isotopic exchange on mercury(II) sulphide and zinc sulphide precipitates.