ʻO kahi hunaola wahie kahi aila electrochemical e hoʻohuli i ka ikehu kemika o kahi wahie (pinepine ka hydrogen) a me kahi mea hana oxidizing (pinepine oxygen) i loko o ka uila ma o ka pālua o nā hopena redox. He ʻokoʻa nā aila wahie mai ka hapanui o nā paila i ke koi ʻana i kahi kumuwaiwai mau o ka wahie a me ka oxygen (maʻa mau mai ka ea) e hoʻomau ai i ka hopena kemika, akā i loko o kahi paila e hele pinepine ka ikehu kemika mai nā metala a me kā lākou iona a i ʻole nā oxide i loaʻa mau i ka o nā puʻukū, koe wale nō i nā paila kahe. Hiki i nā hunaola wahie ke hana i ka uila mau no ka mea ke hāʻawi ʻia ka wahie a me ka oxygen.