The costs connected with utilizing secondary materials (waste) as substitute of the raw materials depend on many factors. In this paper, the emphasis is put on the functioning of the plant depending on: capital costs, ecological unit cost of waste recycling [zł/Mg], unit costs of processing 1 Mg of waste into secondary materials, marketing costs of the obtained product, mass fraction of the substitute obtained from the waste mass, social unit costs [zł/Mg] taking into account such aspects as creating new workplaces, etc., amount of work allocated for the production in fixed units, fixed costs and the amount of the processed raw material (waste). The factors will be considered in two ways: a) maximization of the production with the costs of production fixed, b) minimization of the costs of production with the volume of production fixed. Much research has been done throughout the world to determine the economic and ecological profitability of secondary materials (waste) utilization in the substitution of raw materials. Unfortunately, Poland does not have sufficiently good solutions on this field. The deficiency in such solutions impedes the work of groups of specialists in various fields involved with the rational planning of recycling. These are the result of our mathematical model of economic profitability of the secondary materials (waste) utilization as the substitute of primary materials, at the moment no empirical analyses have been carried out on this issue. We think that it might be a good topic for further applied studies.