The human induced pluripotent stem cells (hiPSCs) derived cardiomyocytes (CMs) (hiPSC-CMs) retain the same genetic information as the donor, and they have been shown to faithfully recapitulate the disease phenotypes of various genetic cardiac diseases. The hiPSC-CMs can be utilized in multiple types of studies and in most cases, the functionality of hiPSC-CMs is of interest. For the functional analyses, the hiPSC-CMs need to be manipulated after differentiation, e.g. enriched or dissociated into single-cell stage. For the functional assessments to be reliable and reproducible, the cell culture environment should support the cells in an optimal manner. The aim of the present study was to evaluate the effect of various differentiation methods, as well as coating materials used for the dissociated cells on the functionality of the differentiated hiPSC-CMs. The different protocols not only had different differentiation efficiencies, but they also yielded functionally different hiPSC-CMs. Additionally, the coating material had a major effect on the functionality of the hiPSC-CMs. The results of the present study emphasize that the cardiac differentiation method and the coating material have a major effect on hiPS-CMs' characteristics. Thus, when different hiPSC lines and results obtained in different labs are compared, extra care should be taken to check the conditions when results are compared.