The paper considers the formation kinetics due to coagulating behaviour of composite particles, represented by a mixture of different materials. New kinetic equations are defined which provide correct account of every formation stage of composite particles and are subject: to direct numerical solution. Analytical solutions are obtained for some simple cases. Generally, self-similar distributions are used to analyse the solutions for their asymptotic behaviour. A method is developed to solve the coagulation kinetic equation of composite particles, with its validity shown by some test problems.