Differential scanning calorimetry is widely employed for the investigation of protein denaturation [1]. However, the scope of presented data is usually limited to the thermal effects and the temperature of the denaturation at a single heating rate. There are just a few systematic studies probing protein denaturation at various heating rates and this limits the understanding of the denaturation mechanism. We have studied the denaturation of hen egg-white lysozyme dissolved in glycerol at a wide range of heating rates. Burova et al. [2] found that lysozyme structure in glycerol resembles the native form and an endothermal heat effect is observed upon heating of the sample. Glycerol solution due to high viscosity and wider temperature range of liquid state represents a good model system allowing the denaturation investigation in the range of heating rates from 0.017 K/s (1K/min) up to 8000K/s (480,000 K/min). Conventional DSCs from Mettler-Toledo (DSC 822e) and Netzsch (204 F1 Phoenix) were used to measure calorimetric curves at heating rates from 1 to 50 K/min. Pyris DSC by PerkinElmer was used to measure denaturation at heating rates of up to 200 K/min. Protein behavior at heating rates from 2 K/s to 8000 K/s was investigated on a fast-scanning chip calorimeter by Mettler Toledo (Flash-DSC 1). In all cases, we have observed an endothermic heat effect upon heating, the position of the peak varied with the heating rate. The results from conventional DSCs were in agreement with each other, on the other hand, the denaturation temperatures measured by Flash-DSC were systematically lower. The Kissinger plot produced to parallel straight lines for the results of conventional and ultra-fast DSCs, and the actual activation energies calculated from the plot are close (246±24 kJ/mol from conventional and 233±17 kJ/mol from Flash-DSC). The discrepancy between the results of conventional and chip DSCs can likely be attributed to the small size and large relative surface area of Flash-DSC samples. On the other hand, no notable deviation from the straight line was observed on the Kissinger plot for the entire range of heating rates. Thus denaturation likely follows the same mechanism even at the highest heating rates measured. Decreased thermal stability of protein in small samples is relevant to the production methods of protein formulations in which the substance is both heated and powdered, such as spray-drying.