Used cooking oil is oil that comes from two or more frying food ingredients. This used cooking oil produces methyl esters with glycerol as a by-product through a transesterification reaction. The goal of this study was to convert and utilize used cooking oil into glycerol, as well as to demonstrate the similarity of functional groups and components found in commercial glycerol using IR and GC-MS spectroscopy. The results of the study found that using cooking oil glycerol and commercial glycerol showed that there were similarities in the 1,2,3 propanetriol groups with retention times that were close to 9.6-10.3 minutes and 9.6-10.13 minutes. The IR spectrum showed the presence of OH, CH, C=O, and C-O groups as well as those found in commercial glycerol, and the glycerol content obtained was 90.17%