The main goal of this project is to develop a new generation of a rotary vane expander for a biomass microcogeneration plant based on Organic Rankince cycle and experimentally validate it by the means of long-term tests. The power output of the unit is 120 kW thermal power and approx. 6.2 kW net electrical power. Essential ambition is to ensure increased reliability, safety and life-span of the expander thanks to the approach of tribology - coatings reducing abrasive wear and the friction coefficient between the vane and stator, vane and stator material analysis and new coated bearings. The components in the expander have to withstand harsh conditions of temperature over 200°C, pressure over 6bars and siloxane vapour with limited lubrication which results in abrasion of vanes and bearings.