Abstract: A fuel modification device comprising a casing having an inlet fitting, an outlet fitting and a flow axis between the inlet fitting and the outlet fitting. The casing encloses a plurality of catalytic pellets held in layers by at least two spaced-apart Monel screens positioned perpendicularly relative to the flow axis. The casing also encloses at least one magnet positioned adjacent to and without touching, one of the Monel screens. The magnet contains at least one element from a group of elements comprising strontium and barium. The catalytic pellets comprises the following composition percentages by weight: 2-7% bismuth; 3-7% mercury; 70-80% tin; and 15-25% antimony. There is further provided a method for treating hydrocarbon fuel within the device wherein an electrolytic action is caused to occur between the fuel and the magnet for causing some of the oxygen molecules in the water impurities to separate from the fuel impurities and to bond to the hydrocarbon molecules as oxygenates.