Abstract: A process is provided for evaluating the global capacity of urine to form chalky renal calculus, the process comprising the steps of pouring a sample of a recently discharged urine into a container plate bearing, on its inner bottom portion, a cup containing a reaction substrate capable of initiating crystallization of calcium in the sample, allowing the sample to rest; discarding the sample from the container plate, washing the container plate with bidistilled water and discarding the water, adding a diluted HCl solution (2.3N) and spreading it over the entire surface of the substrate contained in the cup, adding an aqueous sodium acetate solution (5% w/v) and an indicating solution of ARSENAZO III (0.1% w/v) and mixing the acetate solution and the indicating solution for 15 seconds, to obtain a stained reaction mixture which can be qualitatively and quantitatively evaluated. A kit for carrying out this process is also provided.