In this research work, the viscoelastic properties of jute/polypropylene nonwoven reinforced composites were investigated using dynamic mechanical analysis. The surface of jute fibers was treated with defined content of alkali solution for improving the adhesion characteristics of fiber-matrix interface in the resultant composites. Nonwovens having 40 and 60 wt% jute content were used as reinforcements in jute/polypropylene composites. The magnitudes of peak storage modulus and loss modulus of nonwoven composites improved with an increase in the jute fiber content. The influence of stacking sequence of preferentially and non-preferentially aligned nonwovens on viscoelastic properties of composites was also investigated. The interface adhesion characteristics of composites under dynamic loading conditions were evaluated using adhesion efficiency factor and reinforcement effectiveness coefficient. The homogeneity of alkali treated jute fiber based nonwoven composites has also been analyzed using Cole-Cole plots. (C) 2014 Elsevier Ltd. All rights reserved.