Oxides are often perceived as relatively simple materials that can provide exceptional electrocatalytic activities. However, the assumed simplicity of oxides bears little relation to reality, impeding the progress towards fundamental understanding of electrocatalytic reactions on such materials. Here, we discuss the complexity of oxide surfaces and oxide-electrolyte interfaces and emphasize the challenges and pitfalls that receive little attention but are vital for the future of the field. We also make critical remarks on the existing experimental and theoretical approaches in fundamental electrocatalysis.