The objective of the study was to analyze the kinetics of phosphorus sorption on Rockfos® material in terms of its potential use in water and wastewater treatment. The objective of the study was to ascertain the sorption capacity of the material in relation to its granularity and the predominant sorption process during the removal of phosphorus on this material. The Rockfos® material is manufactured from opoka through a thermal treatment process at 900°C. Tests were conducted on three granulations of the sorbent. The granulations were tested at sizes ranging from 1.0 to 1.6 mm, from 1.6 to 2.5 mm, and from 2.0 to 5.0 mm, using a synthetic solution with a phosphorus content of 1.0 mg/L. The kinetics of phosphorus sorption were analyzed using a variety of kinetic models, including the pseudo-first-order (PFO), pseudo-second-order (PSO), Webber-Morris (W-M), and Elovich (E) models. The degree of fit between the various models and the results of the measurements was evaluated based on an error analysis. The results demonstrated that the pseudo-second-order kinetic model provided the most accurate description of the sorption process on Rockfos® material. This finding suggests that phosphorus sorption is primarily governed by the chemisorption process. The sorption rate constant exhibited the highest value for granulations of 1.6-2.5 mm and the lowest for granulations of 2.0-5.0 mm. The sorption capacity did not exceed 0.05 mg/g in any case, with the highest value observed for material granulations of 2.0-5.0 mm and the lowest observed for grains of 1.0-1.6 mm. The phosphorus removal effects from solution for granulations of 1.0-1.6 mm, 1.6-2.5 mm, and 2.0-5.0 mm were 74.3%, 92.4%, and 97.1%, respectively. These values were positively correlated with pH value.