Spain is the first olive oil maker worldwide. Yearly, the olive oil industry generates large amounts of by-products: olive pomace, tree pruning, pits, leaves and branches. This work presents the experimental and feasibility study of a pilot plant for the conversion of olive tree pruning and olive pits into electrical and thermal power. The pilot plant is composed of a downdraft gasifier, gas cooling-cleaning stage and spark ignition engine with a modified carburetor. The experimental results showed satisfactory cold gas efficiency (in the range of 70.7–75.5%) and good lower calorific value of the producer gas for both raw materials (4.8 and 5.4 MJ kg− 1). Moreover, the plant achieved acceptable values for the electric and CHP efficiency: 15% and almost 50%, respectively. Finally, the investment achieved reasonable profitability index with a payback period of 5–6 years. As a result, the energy recovery potential from the olive industry wastes may represent a good opportunity to promote distributed generation systems.