The function of KCNC1 (potassium voltage-gated channel subfamily C member 1, Ensembl gene identifier ENSG00000129159) is as follows. Voltage-gated potassium channel that opens in response to the voltage difference across the membrane and through which potassium ions pass in accordance with their electrochemical gradient (PubMed:25401298, PubMed:35840580). The mechanism is time-dependent and inactivation is slow (By similarity). Plays an important role in the rapid repolarization of fast-firing brain neurons (By similarity). Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCNC2, and possibly other family members as well (By similarity). Contributes to fire sustained trains of very brief action potentials at high frequency in pallidal neurons (By similarity). {ECO:0000250|UniProtKB:P25122, ECO:0000269|PubMed:25401298, ECO:0000269|PubMed:35840580}.