Human induced pluripotent stem cells directed to the cardiac lineage (hiPSC-CMs) are used in many platforms such as generating models of human genetic diseases and cardiac safety pharmacology whereby compounds bound for regulatory submission are tested on hiPSC-CMs to determine the drug effect on ion channels and action potentials. The cardiac action potential (AP) is an important physiological parameter: (1) the AP initiates excitation in the heart, (2) it modulates the refractory period due to a long AP duration, and (3) associated with each AP is a contraction. Alterations in the expression or gating of ion channels will change the time- and/or voltage-dependent properties and can have marked effects on the AP waveform. The electrophysiological immaturity of hiPSC-CM suggests caution when translating the results to the adult phenotype. This chapter will highlight the electrophysiological similarities and differences of the hiPSC myocyte compared to adult myocytes. We will first contrast AP waveform in hiPSC-CMs and adult ventricle and explore the underlying ionic and molecular basis for these differences. Finally, we will explore strategies employed by various laboratories to potentially improve the maturity of hiPSC-CMs.