In this contribution, the well crystalline cubic CoNiCuFe-PBA catalyst was successfully synthesized with activity surprisingly outperforming the poorer crystalline CoNiCuFe-Oxide catalyst under OER operation. In situ Raman spectroscopy and XPS results demonstrated that CoNiCuFe-PBA undergoes a more complete active phase transformation into a highly reactive amorphous MOOH. This could be attributed to the higher valence state of Ni and Co elements, which are more susceptible to surface hydroxylation and serve as the origin of active sites in OER. By contrast, the CoNiCuFe-Oxide possesses an indispensable and slow step of M 2+ oxidized to M 3+ during the OER process, hindering a large amount of MOOH formed on the surface and leading to poor OER activity. This work provides a practical insight into the design of OER electrocatalysts and highlights the importance of redox-active surface hydroxylation instead of simple amorphous properties.