The reaction of ozone with 1,4-cis-polybutadiene and polybutadiene having the following linking of the butadiene units: 1,4-cis (47%), 1,4-trans (42%), 1,2 (11%) was investigated in CCl4 solution. It was found out by means of IR-spectroscopy and H-1-NMR spectroscopy that the basic ozonolysis products of both elastomers are ozonides and aldehydes. The aldehyde:ozonide ratio was 11 : 89 and 27: 73 for E-BR and BR, respectively. In addition, epoxide groups were detected, only in the case of BR, and their yield was about 10% of that of the alclehydes. On the basis of BR ozonolysis it was established that the ozonide yield from 1,4-trans units is about 50%. By using the aldehyde yields, an evaluation was made of the efficiency of ozone degradation of the two polybutadienes, according to which the respective value of BR is considerably higher than that of E-BR. A reaction mechanism is proposed, which explains the formation of the identified functional groups and the differences in the ozone degradation of the studied elastomers. (c) 2007 Wiley Periodicals, Inc.