Hydrogenated vegetable oil (HVO) diesel fuels have potential to provide reduced carbon footprint in diesel engines and reduce exhaust emissions. Therefore it is a strong candidate for transport and diesel powered machines including electricity generators and other off-road machines. In this research, a waste cooking oil derived HVO diesel was investigated for its combustion performance including ignition delay and heat release, and particulate number emissions including size segregated values. The results were compared to the standard petroleum diesel. A 3 litre direct injection intercooled IVECO diesel engine equipped with EGR was used which has a maximum power output of 96kW and is EURO5 emission compliant. The engine was equipped with an integrated DOC and DPF aftertreatment system. Both the upstream and downstream of the aftertreatment emissions were measured. The tests were conducted at different RPM and loads at steady state conditions. A DMS500 particle size measurement instrument was used for measuring particles between 5 nm and 1000nm. The engine was instrumented with a number of thermocouples so that the engine conditions were closely monitored. Gaseous emissions were measured using a HORIBA 7100 series gas analyser. The results showed that HVO reduced particulate numbers significantly upstream of the aftertreatment system. The particle number emissions were not much different between HVO and standard diesel due to the low particle number concentrations downstream of the aftertreatment system.