Cardiovascular diseases represent the number one cause of death globally, and high prevalence of atherosclerosis in coronary vessels is paving the way for the development of ischemic heart disease and myocardial infarction. The low regenerative potential of the human heart cannot prevent the detrimental remodelling after cardiac injury, and therefore, the use of stem cells (SCs) for cardiac repair has gained great interest in recent years. In spite of ongoing preclinical and clinical trials using SCs in the heart, only little is known about the basic functional properties of these newly generated heart cells, and recent advances in reprogrammation of somatic cells into cardiomyocytes add to the need of thorough characterization of these cells, before functional integration of these cells into the myocardium can be advised. The aim of this study was to characterize the electrical properties of SC-derived cardiomyocytes of different sources and to investigate intercellular coupling between cell pairs. For our comparison, we used mouse embryonic and induced pluripotent SC-derived cardiomyocytes (ESCs, iPSCs) and assessed their function relative to native neonatal cardiomyocytes and cultured HL-1 cells. Parallel electrophysiological measurements using the patch clamp technique and confocal Ca2+ imaging with fluo-3 allowed us to study electrical parameters of the cells and excitation-contraction coupling. In order to study intercellular communication between neighboured myocytes, expression of gap junction proteins was confirmed in immunocytochemical assays and the gap junction permeant fluorescent dye calcein was used to measure metabolic coupling between cells. In differentiated SC-cardiomyocytes, we have identified two distinct populations of cardiomyocytes, spontaneously active and silent but excitable cells, as reflected by the shape of their action potentials. They functionally express the pacemaking HCN channel in spontaneously active cells and cardiac-specific voltage-dependent Na+, L- and T-type Ca2+ channels, as confirmed by current properties and pharmacology. Immunocytological examination revealed strong expression of the cardiac gap junction protein connexin-43. Functional tests of intercellular coupling confirmed electrical coupling between SC-cardiomyocytes. However, permeation kinetics of dye transfer in SC-cardiomyocytes were similar to HL-1 cells, but significantly reduced in comparison with neonatal cells. In conclusion, we provide a clear physiological profile of single and coupled SC-cardiomyocytes of different origin and evaluate their functional similarities with native cardiomyocytes and HL-1 cells. Despite strong electrophysiological parallels, the disparities in metabolic communication need to be carefully considered for future use of these cells in cardiac regenerative therapy.