Kv11 potassium channels are important for regulation of the membrane potential. Kv11.2 and Kv11.3 are primarily found in the nervous system, where they most likely are involved in the regulation of neuronal excitability. Two isoforms of human Kv11.2 have been published so far. Here, we present a new splice variant that is present in human brain as demonstrated by reverse transcription PCR. Heterologous expression in Xenopus laevis oocytes revealed a 30-mV shift in the voltage dependence of activation to more depolarized potentials and slower activation together with faster deactivation kinetics compared to hKv11.1. Further, we have cloned and electrophysiologically characterized two splice variants of hKv11.3. When expressed in X. laevis oocytes, both isoform 1 and isoform 2 elicited robust currents with a striking transient current component caused by delayed inactivation. The different current characteristics of the isoforms presented in this work may contribute to the regulation of neuronal excitability.