The photocatalytic performance of pristine and rare earth elements (La, Ce, Pr, Er, Yb) doped zinc oxide was tested toward the abatement of a model pollutant in MilliQ water and wastewater matrices. ZnO doped with Ce, Er and particularly with Yb exhibited photoactivity higher than bare zinc oxide and the benchmark TiO2 P25, especially in wastewater matrix. Several electrochemical investigations were performed via chronopotentiometry and cyclic voltammetry aimed to shed light on the reasons why the diverse materials behaved differently. From the overall data a complex picture emerged, where there is not a single property of the materials evidently outperforming the others. Nonetheless, from the analysis of whole data a limited role of doping emerged for La and Pr, doping with Er improved the photocurrent, doping with Yb favored a better accumulation of photoelectrons, and doping with Ce promoted a faster electron transfer.