Background and Objectives: Antibiotics are potential pollutants that represent an important environmental problem because of their toxic effects on the food chain and aqueous streams. The objective of this research was to study the adsorption of penicillin G on to chestnut shell as an inexpensive adsorbent. 
Materials and Methods: This study was performed at laboratory scale  and batch system. We studied the influence of process variables such as adsorbent dose, initial PEN G concentration, pH of solution, contact time, and breakthrough curves. In order to find out the possibility of reuse, desorption study was also carried out. The surface characteristics of adsorbent were investigated using Fourier Transform Infra-Red and Scanning electron microscope. Equilibrium study data were modeled using Langmuir, Freundlich, and D-R models.  Moreover, kinetic studies were done by three models of pseudo first order, pseudo second order, and intra-particle diffusion.
Resuls: The maximum PEN G removal achieved was 92%, at pH 3, adsorbent dose 0.1 g/l and contact time 120 min. The Langmuir equation (R²=0.99) provided the best fit for the experimental data. It was also found that adsorption of PEN G by chestnut shell followed pseudo- second order model (R²= 0.992).
Conclusion: According to the results obtained, chestnut shell appears to be a suitable, low cost and efficient adsorbent for removing PEN G from waste streams.