This invention relates to a composite of a melamine derivative, particularly a liquid melamine derivative, and carbon black. A representative melamine derivative is, for example, comprised of an alkoxymethylmelamine such as hexamethoxymethylmelamine. The invention further relates to a rubber composition containing such composite of a melamine derivative and carbon black and to a rubber composition containing such composite as a methylene donor in combination with a methylene acceptor and the reaction product thereof in situ within said rubber composition. Such rubber composition may be a component of an article of manufacture, which may contain or be exclusive of, wire reinforcement, such as for example a component of a tire, vehicular track or industrial belt or hose.