The flow cell modeling clinical conditions have been used to study the interaction between dilute chemolytic solutions and large calcium oxalate renal stones. The stone treatment with 5% disodium ethylenediaminetetraacetate aqueous solutions or citrate buffer are found not to provide notable disruption of the samples studied. The significant improvement is reached with the mixed compositions containing both natural and synthetic chelating reagents:citrate and ethylenediaminetetraacetate ions as well as an antibiotic. Description of the chemolytic irrigation, numerical results and their possible clinical application are the main topic of the present research.