By expanding the research and development of the pharmaceutical industry, the number of pharmaceutically active substances discovered over time is growing. Newly discovered pharmaceuticals can get into the environment through waste streams and cause its contamination. Knowing the physicochemical properties of the pharmaceuticals and the degradation processes they are subject to in the environment is crucial for predicting their behavior. One of such unexplored pharmaceuticals is cefdinir. Cefdinir is a third-generation cephalosporin antibiotic, and finds the greatest use in the treatment of bacterial infections of the ear, sinus, throat and skin. Sorption is an example of a process that this drug is subject to in the environment. Cefdinir can be sorbed on natural soil and sediments, and sorption intensity will depend on factors such as ionic strength, pH-value and sorption time. Through a series of experiments, the aim of this study was to examine the process of sorption of cefdinir on natural soil and sediments sampled throughout the Republic of Croatia. The experimental data are described by the models of sorption isotherms - Linear, Freundlich and Dubinin – Radushkevich model – of which the highest correlation coefficient (R2> 0.99) was obtained with a Linear model. The sorption coefficient (Kd) proved to be the lowest for sediment Pakra and the soil of Graĉac, and the highest for sediment Lonja and soil Josipovac. With the increase in ionic strength and pH-value, the value of the sorption coefficient decreases. In order to describe the kinetics of absorption of cefdinir, the pseudo first order model and the pseudo second order model were used. The best correlation with experimental data for the sediment of Glina and the soil of Bruvno was given with the pseudo second order model. The desorption of cefdinir is described by an intra particle diffusion model according to which the intraparticle diffusion rate constant for the soil of Bruvno is greater than the one for the sediment of Glina. The higher the initial concentration of the standard cefdinir solution, the larger the value of the intraparticle rate constant.