Palm biodiesel is known to have advantages of low emissions, oxygen content and high cetane number, but it has high viscosity properties and low heating value which will affect the performance of diesel engines. Meanwhile, hydrogen gas has a high calorific value and is flammable, as well as low exhaust emissions which can correct the shortcomings of biodiesel. This research was conducted on a dual fuel diesel engine. One of the aims of this study was to know combustion characteristics on a single- cylinder diesel engine, with constant speed 50% load 2500 watts. The first step is to vary the flow of hydrogen by 2.5; 5; 7.5; and 10 lpm. At medium loads the value of the combustion chamber pressure increases with the addition of hydrogen to the biodiesel. HRR at medium loads increase compared with single fuel biodiesel by 7.74%. Ignition delay dual fuel at the hydrogen mixture with a flow rate of 2.5 L per minute (lpm) demonstrates the shortest ignition delay at medium engine loads. The duration of combustion dual fuel at all loads is relatively the same as compared to single fuel. At medium loads the addition of hydrogen concentration to biodiesel with h2 2.5 lpm increases the maximum value of knocking pressure.