Poly(epsilon-caprolactone) (PCL) composite samples were prepared by polymerization and direct molding. The starting compound was epsilon-caprolactone monomer liquid combined with cellulose and inorganic fillers, using aluminium triflate as a catalyst at 80 degrees C, for 6 or 24 h. Cylinder-shaped PCL composite samples with a homogeneously dispersed cellulose filler were prepared with (-)M(n) = 4 600 ((-)M(w)/(-)M(n) = 2.9). The mechanical properties of the PCL composite samples were studied using compression test methods. The strength of a PCL composite with 50 wt.-% cellulose filler (10.8 MPa) was found to be lower than the PCL sample without fillers (19.2 MPa). The biobased content of the PCL composite with 50 wt.-% cellulose filler (51.67%) measured using accelerated mass spectrometry (AMS) was slightly higher than the carbon ratio of cellulose in the starting powder samples (41.3 mol-%). The biobased content of the polymer composite powders by AMS was found not to be affected by the presence of inorganic fillers, such as talc. The rate and extent of biodegradation, caused by Amano Lipase PS, of the PCL composite sample with cellulose filler (40% degradation in 4 d) was the same as that of a PCL sample without the cellulose filler.