Biocomposites were prepared using coconut coir fiber that has been subjected to various treatments and polylactic-acid (PLA) as a matix. The volume fraction of the fibers in the PLA composites was fixed at 40 %. The composite with NaOH-treated fiber absorbed the most water. In general, biocomposites made with coconut coir fiber that had been treated with NaOH followed by acrylic acid (AA), had a greater tensile and flexural strength than did untreated or fibers treated only with NaOH. Tensile and flexural strengths of the biocomposites decrease after 6 h and decrease drastically for 192 h following soaking in the water. Tensile fracture and surface biodegradation were observed using the SEM. We also studied the comparison of biocomposites with coir fibers that had been treated with alkali followed by 0.5 % AA for 0.5 h at room temperature and at 70 °C.