TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In method (M1), the sequence comprising reaction time interval and the regeneration time interval is repeated at least one times. The ratio of the reaction time interval over the regeneration time interval is 1-30. The regeneration time interval is 2-5 seconds. The second mixture is ignited prior to contacting the partial oxidation catalyst. The feedstock is a liquid hydrocarbonaceous feedstock and has a final boiling point up to 400 (preferably 250-400)degrees C. During the reaction time interval, the liquid hydrocarbonaceous feedstock is evaporated by mixing the feedstock with a first part of the molecular oxygen to form an intermediate mixture comprising feedstock and molecular oxygen and igniting the intermediate mixture. The oxygen-to-carbon ratio in the intermediate mixture is 0.01-0.4 (preferably 0.01-0.15, especially 0.02-0.10). The overall oxygen-to-carbon ratio in the reaction time interval is 0.40-0.75 (preferably 0.45-0.65). The oxygen-to-carbon ratio in the regeneration time interval is 2-5. EXAMPLE - ARCO Ultra low sulfur diesel number 2 (RTM: diesel fuel) was converted to a hydrogen-comprising gas over a partial oxidation catalyst. The duration of the on-period (reaction time interval) was 180 seconds. Diesel fuel and exhaust gas were supplied to the catalyst with an oxygen- to-carbon ratio of 0.53. The duration of the off-period (regeneration time interval) was 5 seconds. During the off-period the catalyst was contacted with a mixture of diesel and exhaust gas having an oxygen-to-carbon ratio of 3.7. Prior to contacting the catalyst, the mixture was ignited using a glow element powered at 8 V and 17 A. For a period of 90 minutes, a hydrogen-comprising gas was produced according to on/off operation i.e. continuous partial oxidation (test) and a steady state process (comparative). The mixture of diesel and exhaust gas was introduced at a temperature of 125degrees C. The hydrogen yield was 0.106/0.102 mol of syn gas/g of fuel and % conversion was 89.7/87.7% for test/comparative experiment respectively. Thus the on/off operation, showed an improved catalyst performance compared to the steady state operation.