Abstract In this work, we have synthesized biocomposite films based on starch reinforced with microcrystalline cellulose (MCC) with different MCC/starch weight contents (0, 1, 3, 5, and 7 %). These films were characterized by various techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX), which showed dispersed and biocompatible structures for MCC and starch. It was found that the increase in MCC content (from 0 to 7 wt%) led to decreasing the water solubility, and reducing the absorption coefficients, transmission percentages and electrical conductivity. However, the improvement of dielectric and mechanical properties was demonstrated by decreasing the dielectric loss tangent and increasing the Young’s modulus, respectively making them suitable for dielectric and mechanical applications.