Tests were carried out with the aim of studying the influence of the fuel-injection equipment (FIE) on gaseous and particulate-mass (PM) emissions when using water-in-fuel emulsion. The tests included different pump-nozzle combinations, a new slide-valve-type fuel injector, water-in-fuel emulsion and different fuel-sulphur contents. The NOx reduction is compared with the results of several other tests in large two-stroke engines using water emulsions.A NOx reduction of approximately 25% was obtained using a large pump-nozzle combination and 30% added water, without deterioration in the specific fuel oil consumption. The NOx behaviour is correlated to the injection intensity as well as to a water-amount effect.Fuel sulphur has a major influence on PM, as sulphates account for approximately 35% of the total PM when operating on ‘normal’ heavy fuel. A linear approximation estimates the ‘non-sulphur’ fuel PM at between 30 and 60 mg/Nm3, depending on the FIE system. No simple correlation was found to explain the PM behaviour in the test.