Lignocellulosic fibers have gained a major interest in to use as reinforcement in polymer matrices due to their availability, low cost and compatibility with the environment. This work deals with the development of biocomposite materials based on polyhydroxybutyrate-co-valérate (PHBV) containing 20 w.% of natural fiber i.e., alfa fiber and olive husk flower (OHF). The effect of fiber type on thermal, mechanical and morphological properties of biocomposites was evaluated. Young modulus of PHBV was increased when alfa fiber and OHF each added either alone or both. From the SEM images, it was observed that OHF was uniformly dispersed in PHBV compared to alfa fiber. This may be due to the size of fiber. Indeed, the result obtained from a particle size distribution analysis showed that the size of particles of OHF varied between 1 µm to 150 µm. More than 90% of OHF had a diameter lower than 96 µm, however, 90% of alfa fiber was obtained with a diameter between 100-110 µm. For OHF having lower particle sizes most of the fiber surfaces are covered with the matrix material attesting for adequate compatibility between the two phases.