Heteropoly compounds (HPCs) can be used as excellent catalysts for both acid-catalyzed reactions and oxidation reactions due to their acidic and redox properties, which can be controlled at molecular level. Practical interest in the application of HPC in industrial catalysis is caused by the wide possibility of varying their catalytic properties by adding different elements. Generally, in acid-catalysed organic conversions, the HPCs are deactivated by coke formation [1, 2]. The pure and palladium doped 12-tungstophosphoric acid - H3PW12O40 (HPW) and its caesium salts CsxH3-xPW12O40 (x=1, 2, 2.25 and 2.5) were prepared and characterized by thermal analysis, FTIR, XRD, BET and XPS methods. The effect of palladium on the coke content during the dehydration of ethanol in the temperature range of 200-350 °C was determined. Above 300 °C, a strong deactivation of the catalysts was caused by the coke formation. Coking was analyzed by temperature-programmed oxidation (TGA/TPO) method using a thermo analyzer system, Mettler TGA/SDTA 851/LF/1100. Experiments were carried out using about 20 mg samples into alumina crucibles of 150 μl. The heating rate was 10 °C /min in the range of temperature 25-650 °C with an isothermal step at 300 °C for 30 min. The measurements were conducted in dynamic atmosphere of nitrogen (50 ml/min) and finally under flow of air for 30 min to oxidize the catalysts. By switching from N2 to air at the same flow rate, the remaining coke deposited on the catalysts was burnt out. The amount of coke precursor present in the catalysts was calculated by the difference between the initial mass of spent catalyst sample after isothermal heating at 300 °C (temperature of reaction test) and the sample mass heated in nitrogen at 650 °C. Soft coke is removed from the samples through volatilization in inert nitrogen and refers to high molecular weight aliphatic oligomers. The amount of hard coke present in the catalysts was calculated as the difference between samples mass heated in nitrogen at 650 °C and mass loss of sample at 650 °C in air, when the coke was burnt out. Hard coke refers to heavy polynuclear aromatics. The sum of coke precursor and hard coke represent the total coke. The formation of coke during the ethanol dehydration over HPCs does not affect the Keggin structure which led us to conclude that such catalysts can be regenerated in air and regain their catalytic activity for a short time.