Atenolol (ATL) was removed with a rectangular staircase photocatalytic reactor (RSPR) using immobilized ZnO under solar irradiation. The effects of operational parameters such as flow rate, pH, and initial ATL concentration were examined. The highest degradation was obtained after 240 min photocatalytic reaction. The effects of different scavengers proved that the ATL degradation was mainly due to the direct oxidization with OH center dot radicals, whereas, the h(+) and O-2(center dot-) radicals played a minor role in the degradation process. Five repetitive operations of RSPR allowed for reaching 77 +/- 3 % degradation of ATL for each cycle. Kinetic data indicated that the photocatalytic kinetics followed the global matter balance model.