The Full Form of MDO is Marine Diesel Oil.

Marine Diesel Oil (MDO) is a type of fuel oil and is a blend of gasoil and heavy fuel oil, with less gasoil than intermediate fuel oil used in the maritime field. Marine Diesel Oil is also called “Distillate Marine Diesel”. MDO is widely used by medium speed and medium/high speed marine diesel engines. It is also used in the larger low speed and medium speed propulsion engine which normally burn residual fuel. Those fuels result from a catalytic cracking and visbreaking refinery. Marine diesel oil has been condemned for its nimiety of sulfur, so many countries and organizations established regulations and laws on MDO use. Due to its lower price compared to more refined fuel, MDO is favored particularly by shipping industry.