The development of methods for investigating protein-protein interactions in native complexes and in living cells is an important goal in proteomics. Chemical cross-linking represents a potentially powerful approach to this goal. In this article, we review the application of recently developed oxidative cross-linking techniques to this problem; the involved reactions, mediated by high-valent metal-chelate complexes, are highly efficient in many cases, extremely rapid and do not require chemically modified proteins, although new chemical design strategies can broaden the scope of applications. Some promising applications of this chemistry to model systems is reviewed, including the fast and convenient covalent labelling of G-protein-coupled receptors (GPCRs) in intact cells, with an emphasis on the perspectives of mapping signalling events triggered by these complexes. Progress towards resolving the outstanding problems of signalling network elucidation, in addition to chemical and analytical issues that must be addressed, are discussed.