The anodic behaviour of a nickel electrode has been investigated in KOH electrolytes below and above the oxygen evolution potential. As the literature reports a wide range of behaviours, initial repetitive cyclic voltammetry in 1 M KOH was compared to 30 wt% KOH (i.e., that used in alkaline water electrolysers) and it was found that a process in addition to the normal alpha-Ni(OH)(2)/gamma-NiOOH and beta-Ni(OH)(2)/beta-NiOOH occurs in the more concentrated electrolyte. It is also confirmed that the initial hydroxide layer formed anodically from metallic nickel is not alpha-Ni(OH)(2), but a layer which is more readily reducible than alpha-Ni(OH)(2). At higher potentials, while in-situ XAS suggested that gamma-NiOOH is not transformed to any further phase up to 0.665 V vs HgHgO in 1 M KOH, after extensive OER (at least 40 hrs) in 30 wt% at 50 mA cm(-2), an additional phase can be identified by cyclic voltammetry. Overall, during galvanostatic oxygen evolution, the nickel anodes follow an ageing behaviour characterised by a brief activation period, a short period of high activity (i.e., low overpotential) followed by deactivation and eventually stable but poor activity. While no clear evidence was obtained to identify the most active phase for oxygen evolution, it is likely that this is related to beta-NiOOH and confined to the very surface of the electrode. (C) 2015 Elsevier Ltd. All rights reserved.