The invention provides a metal alloy fuel catalyst for decontaminating a hydrocarbon fuel, including diesel and bio-diesel fuel, of a bacterial contamination and for improving fuel combustion. The metal alloy fuel catalysts preferably includes about 70% Sn, about 22% Sb, about 4% Bi, and about 4% Pb, although other formulations are possible. The fuel catalyst can take the form of an in-line component in a fuel system or be coated within a fuel storage container.