The work presented in this thesis is concerned with some fundamentalinvestigations on combustion of the solid and liquid biomass productsform tge palm tree species, Elaess guineenssi. Liquid oils extracted from the palm fruits included the crude palm oil (CPO), refined palmoil (RBD) and its methyl ester form, and these together with the oil palm solid wastes were investigated. They were compared with the commercial fuels, diesel and coal respectively a source of energy.In the liquid fuel investigations, the physical, chemical and combustionproperties were analysed. A suspended droplet technique was used in theinvestigation ofthe ignition delay time and the combustion rate constant.It was found that the refined palm oil had longer ignition delay timebut higher burning rate that diesel fuel (gas oil) and its methyl esterform was about the same as diesel fuel. Spray characterisation of allthe fuels was conducted using a Lucas-CAV diesel engine injector withMalvern 2600c Particle Sizer and Dantec Particle 60X FiberFlow Analyser.It was found that the RBD palm oil displays inferior spray characteristicspattern showing larger droplet size distributions which could be oneof the reasons of carbon build-up in the combustion chamber. A simplecombustion model applicable to diesel engines was developed for the analysis of the heat release rate. The results also show the RBD palm oil can be used directly for spray fired boilers abd furnaces. In the case of oil palm solid waste combustion emphasis was placed on the fluidised bed combustion of palm shell and it compared to that of coal. The primary fuel characterisation of palm shell was investigation and thermal gravimetric was condusted. Devolatilisation of palm shell and coal were made and surface studies of chair particles usingscanning electron microsope and nitrogen adsorption B.E.T. method were used. Results indicated theat volatile matter from palm shell are higher compare to coal, leaving smaller pore holes having larger surface area then coal char. This could be the one of the reasons that higher reactivity occurs in palm shell duting fluidised bed combustion. It was also established that in fluidised bed combustion of palm shells, most of the volatile matters burn in hte freeboard and required more air for combustion. In contrast coal burns most of the time in the dense phase resulting in higher heat release in the dense phase. Combustion of charwas analysed and it was found that palm shell char burn by a diffusioncontrol combustion process.It was concluded the the palm oil tree can provide satisfactory liquidfuels for spray combustion in stationary srray equipments and for diesels. The solid waste is also a satisfactory fuel for combustion ina fluidised bed.