The catalytic supercritical water gasification of isopropanol (450 degrees C, 30 MPa) over Ru catalysts supported on carbon and metal oxides was performed in a fixed-bed plug flow reactor. The Ru loading was between 1.2 and 2%. The catalyst stability over a period of 50h was in the order: Ru/C > Ru/ZrO2 > Ru/Al2O3. Ru/TiO2. Considerable coke deposits were found on Ru/Al2O3 and Ru/TiO2, which suggests that coke formation was responsible for the loss of activity, whereas the coke content was much lower on Ru/C and Ru/ZrO2, which confirms their better coking resistance. Clearly, Ru/C was the most stable catalyst as a loss of only 3% of its initial activity was measured. The high Ru dispersion of Ru/C and Ru/ZrO2 was beneficial for the improvement of the catalyst stability because of the higher gasification rate versus the coke formation rate.