The main target of this project is to propose a rotary oven cocoa drying unit that uses biomass combustion to produce heat necessary for drying process. We applied functional analysis to choose suitable designed mechanism using available standards for calculations. Drawing software enable us to draft out reliable components. Assembly of these components led to an oven with a drying capacity of 250kg/h under a constant flow of heat rated 1.86 m3/s at a constant temperature T= 83 °C. For a drying cycle, it is feed with 29 kg of sawdust to burn at a temperature of 260 °C and produce 164.24 kW of energy. Keys word: Valorization, biomass, cocoa drying, rotary oven, drying unit