'electrolyser' originates from modern English, specifically from the verb 'electrolyse' plus the agent suffix '-er', where 'electro-' derives from Greek 'ēlektron' (meaning 'amber', later associated with electricity) and 'lysis' comes from Greek 'lysis' (meaning 'loosening' or 'splitting').

'electrolyser' developed from the 19th-century term 'electrolysis' (coined using Greek elements) and the verb 'electrolyse'; the agent noun form 'electrolyser' (and the US spelling 'electrolyzer') emerged in modern English to denote a device that performs electrolysis.

Initially the roots referred to the process of 'splitting' by electrical means ('electrolysis'); over time the derived noun came to mean not the process but the machine or apparatus that carries out that process.