The formation of infectious urinary stones is a complex physicochemical process that occurs in urine. Infectious urinary stones are formed only when the urinary tract is infected by microorganisms producing urease. The presence of urease-positive bacteria in urine causes the elevation of the concentration of ammonia and carbon dioxide. As a consequence, the presence of bacteria in the solution of urine causes the changes in concentration of various ions and influences on the chemical equilibria of various complexes in urine. In this paper, the analysis of chemical complexes created in the solution of artificial urine of basic composition and with additional quantity of ammonia and carbon dioxide is presented. These two cases correspond to the situation without and with infection within the urinary tract, respectively. In other words, in this paper we try to answer to the question how the presence of urease-positive bacteria in urine influences on the chemical equilibria of various complexes in urine. (C) 2016 Elsevier B.V. All rights reserved.