In this article, we discuss that glycerol by-product can be a good feedstock for crystalline poly(lactic acid) (PLA). The glycerol by-product containing 46% of glycerol is first converted into racemic lactic acid by an alkaline hydrothermal reaction. The racemic lactic acid is then converted into a stereomixture of lactide, followed by a purification process to obtain racemic lactide. The racemic lactide is stereoselectively polymerized into isotactic PLA, which is crystalline with a high melting temperature of 208 degrees C.