This paper presents the relationship between processing, formulation and properties of polypropylene (PP)/triticale straw biocomposites. The effects of triticale content, the presence of maleic anhydride grafted polypropylene (PP-g-MA) as coupling agent and of calcium oxide (CaO) as reactive additive on biocomposite properties are discussed. Biocomposites were prepared by twin-screw extrusion process and injection molding. The compounded biocomposites were characterized in terms of morphology, rheology, thermal and mechanical properties, recycling behavior and fire resistance. The morphological observation shows that a good dispersion of triticale straw in PP can be achieved during the compounding step for all the formulations. Biocomposite viscosity and mechanical properties were increased when triticale straw content increased up to 40 vol%. Mechanical properties were further improved in the presence of PP-g-MA and CaO. The reactive additive, CaO, provides superior strength, modulus as well as fire resistance, and upgrades the triticale straw classification from regular filler to reinforcement category. All biocomposites formulated exhibit a good recycling ability. The results demonstrate that triticale straw acts as a good reinforcement and has a great potential in thermoplastic composites field if the processing technique and formulation are appropriate.