Thermal behaviour of different starch derivatives, i.e. starch esters and ethers having degree of substitution (DS) in the range of 0.02-0.18 were studied. Potato, maize and wheat starches were used. Measurements were carried out by coupled thermal analysis/mass spectrometry method (STA-MS) in air atmosphere. The major DTG peak during the investigation for starch derivatives is observed below 300 degrees C. The mass loss up to a temperature of 300 degrees C is about 50%. The most abundant ions found are H2O+ and CO2+. For the studied starch derivatives with a low degree of substitution (DS < 0.18) no correlation was found between thermal stability and the level of substitution regardless of the nature of substitution.