Polymer/clay and polymer/nanodiamond composites were prepared via solution dispersion, melt processing and new so-called colloid-deposition techniques. The following polymers have been used as matrices: hydroxypropylcellulose, polysulfone and styrene-acrylonitrile copolymer. For estimation of particles distribution in polymer matrices the optical microscopy, SEM and TEM methods were used. The X-ray results demonstrate that at least at some compositions, the technique employed was successful to intercalate the clay structure. It was found that particles addition (at small concentration) to polymeric liquids leads to decrease of viscosity. Tensile testing showed considerable improvements of mechanical properties.