The function of KCNH8 (potassium voltage-gated channel subfamily H member 8, ENSG00000183960) is as follows. Pore-forming (alpha) subunit of a voltage-gated delayed rectifier potassium channel that mediates outward-rectifying potassium currents (PubMed:11897058). Elicits a slowly activating, non- inactivating and slowly deactivation outwards potassium current at depolarizating voltages from -30 mV to +50mV (PubMed:11897058). Shows no obvious change in the activation rate from different holding potentials. Activation is strongly dependent on the pH of the external solution (By similarity). {ECO:0000250|UniProtKB:Q9QWS8, ECO:0000269|PubMed:11897058}.