Abstract: Cis 1,4-polybutadiene samples prepared with different catalysts haye different physical, mechanical properties and processibility as well.It is related to their molecular weight distribution, microstructure and contents of the branched chains. The present paper describes the characterization of various kinds of cis 1,4-polybutadiene by gel permeation chromatography (GPC) coupled with low angle laser light scattering spectrometry (LALLS). Satisfactory results are obtained for both linear and branched samples.