Polyethylene (PE) is the most widely used thermoplastic polymer due to its mechanical properties, easy processability and low cost. However, polyethylene has a low glass transition temperature that limits its usage in high temperature applications. In order to improve the thermal stability and mechanical properties of polyethylene, crosslinking method is frequently used in the literature. Coagents are multifunctional vinyl monomers highly reactive against free radicals. They increase the crosslinking efficiency acting as a bridge between polymer chains.The aim of this study is to investigate the mechanical, thermal and rheological properties of various types of polyethylene (LDPE, LLDPE-C6 and LLDPE-C8) cross-linked in the presence of coagent and peroxide (PRX). 2 phr of 1,2-polybutadiene (PB) was used as a cogent and 1 phr of di-tert butyl cumyl was used as peroxide. PRX, coagent and polyethylene were compounded by an Xplore model twin-screw microcompounder at 135’C, and they were cross-linked under 15 MPa pressure by using a hot-press at 175˚C. In order to characterize properties of samples, morphological, mechanical, thermal and rheological tests were examined. The rheological test results showed that the crosslinking density of LLDPE-C6/PB/PRX blend was higher than that of LLDPE-C8/PB/PRX and LDPE/PB/PRX blends. Besides, storage modulus and complex viscosity values were also increased with crosslinking. Tensile test results indicated that the elongation at break and the tensile strength values of the LLDPE/PB/PRX blends increased as compared to the LDPE/PB/PRX blend.