This paper reports a comparative experimental study on the thermal behavior of organic lightemitting diodes (OLEDs) under varying electrical driving conditions. Temperature distributions were simultaneously measured at both the top emission surface and rear substrate surface using K-type digital thermocouples and high-resolution infrared thermography over continuous 120 minutes operational periods. The OLED device was characterized at multiple direct current levels (45 mA, 30 mA, 20 mA, and 5/15 mA) to establish comprehensive thermal profiles. Experimental results reveal that device surface temperature, used as a proxy for junction temperature, exhibits strong positive correlation with applied current density, with thermal steady-state conditions achieved between 60–110 minutes depending on operating conditions. The rear surface consistently exhibited temperatures 3–6 °C higher than the top surface across all current levels, indicating heat accumulation within the substrate and the thermal resistance of the multilayer OLED structure. Thermal imaging revealed temperature gradients of approximately 1.5–2.5 °C between device center and edges at steady state. Comparison of measurement methodologies shows infrared thermography consistently recorded temperatures 1–3°C higher than thermocouple measurements due to emissivity considerations and surface radiation effects. These findings quantify the thermal management requirements for OLED devices and establish baseline thermal characteristics essential for reliability modeling, lifetime prediction, and packaging optimization in display and lighting applications. The proposed dual-measurement framework establishes a practical experimental benchmark for validating electrothermal simulations of OLED devices. Accurate experimental thermal characterization remains a prerequisite for predictive electrothermal modelling of emerging OLED technologies.