The objective of the research study was to compare the activity of diastase in varietal honey as well as to evaluate the thermal stability of the enzyme during dissolving and long-term storing honey. The study material consisted of 25 varietal honeys from apiaries located in the Podkarpacie region including multifloral, goldenrod, rape, tilia, and honeydew honeys. The diastase number (DN) was determined using a Phadebas Honey Diastase test in fresh, long-term stored and heated honeys. The highest activity of α-amylase was found for the goldenrod and tilia honeys (32.65 and 31.47 DN, respectively), the lowest for the rapeseed honey (15.32 DN) All the tested samples met the limits as specified in the regulations in force. The dark honeys were characterized by a higher diastatic number than the light honeys, and the Pearson’s correlation coefficient between the colour (measured as an absorbance unit with λ = 450 nm) and the diastase number was 0.751. While storing the honey samples at a temperature of 20 ± 2 ºC for a period of 24 months, a 17 to 42 % decrease in the diastase activity was reported depending on the variety. The diastase activity decreased with the increasing temperature of solvent used to diluted the honey, whereas the enzyme remained stable in the temperature range between 20 and 40 ºC. As soon as the temperature of 60 ºC was exceeded, a drastic inhibition of the enzyme activity was reported. In addition, the honey solution, stored at 20 ± 2 ºC for 24 hours, did not lose enzymatic activity. It was proved that the honey used to sweeten warm (below 60 ºC) beverages did not completely deactivate the diastase.