Metal-containing diamond-like carbon hard coatings (Me-DLC) consist of nanometre size metallic particles, embedded into an amorphous hydrocarbon matrix. Their mechanical, tribological and electrical properties are strongly influenced by the size and density of metallic clusters in the him. In this paper a systematic investigation of mean sizes and mean centre-of-mass distances of metal clusters in Me-DLC films is presented. Films with four different kinds of metal (gold, platinum, tungsten and iron) and metal contents ranging from 0 to 50 at.% are analysed, each by four complementary analytical techniques: small angle X-ray scattering, wide angle X-ray diffraction, transmission electron microscopy and scanning tunnelling microscopy. Increasing particle radii and particle distances in the range of 1 to 5 nm and 2 to 10 nm respectively are found with increasing metal content of the film. Cluster sizes and distances correlate to the melting-point and the carbide forming behaviour of the metal. The results of different materials are compared and the suitability of analytical techniques for this particular application is discussed.