Pyrolysis-gas Chromatographic studies are presented for 1,4- cis-, 1,4- trans-and 1,2-polybutadiene. 1,4-Polybutadiene and 1,2-polybutadiene can be differentiated by the butadiene peak in the 1,4-polybutadiene pyrogram and a characteristic peak of 1,2-polybutadiene pyrogram. We found that there exists a hydrocarbon peak believed to be 1,8-dimethylperhydrophenanthrene, which is given only by 1,4- cis-polybutadiene.