Natural fiber reinforced composite materials have found many applications in various industries due to the fact that they are naturefriendly, low-cost and sustainable materials. In this study, jute fiber reinforced and cork based sandwich composites were produced and their viscoelastic properties were investigated. First, thin jute/polypropylene (PP) composite plates were produced by using jute/PP nonwoven fabrics and PP granules. Then these plates were placed on top and bottom faces of a cork plate and consolidated under pressure to produce sandwich composites. Dynamic mechanical analysis (DMA) was performed to determine the viscoelastic properties of the produced samples. It was found that sodium hydroxide (NaOH) treatment of fibers before composite preparation lead to higher mechanical properties of the composites. The produced sandwich composites can be used in construction industry as insulation materials and office partition panels as well as in automotive industry.