TiB2-Cu composites in a nanostructured state are candidates for high-strength conductive and erosion-resistant materials. In this work, we studied formation of nanostructured TiB2-Cu composites under shock wave conditions. We investigated the influence of preliminary mechanical activation (MA) of Ti-B-Cu powder mixtures on the peculiarities of the reaction between Ti and B under shock wave. In the MA-ed mixture the reaction proceeded completely while in the nonactivated mixture the reagents remained along with the product – titanium diboride. The size of titanium diboride particles in the central part of the compact was 100-300 nm. This research shows that shock wave synthesis in mechanically activated powder mixtures with simultaneous compaction of the composite is a promising way to materials with submicron and nanostructures.