Blends of high-density polyethylene (HDPE) with chlorinated polyethylene (CPE) were generated using melt mixing. CPE of two different chlorination contents was used and its amount in the blends was varied from 1% till 30%. The rheological, thermal, mechanical, and morphological properties of the blends were characterized along with miscibility analysis. In general, better mixing of the CPE polymer in HDPE was observed at lower CPE concentration and reduced mixing or immiscibility occurred at higher concentration of CPE. However, the extent of immiscibility was different in both CPE25 and CPE35 systems. The rheological analysis of the data using Cole-Cole, Han-Chuang and van Gurp plots confirmed the miscibility of CPE25 blends (except for 30% CPE25 blend at lower frequency) whereas CPE35 blends with 10–30% CPE content were immiscible. Highest increase in the rheological properties (complex moduli) was observed at 2% CPE content. The mechanical properties of the CPE25 blends were superior than the corresponding CPE35 blends especially at higher CPE concentration where effects of immiscibility as well as matrix plasticization played a role. The morphology characterization using TEM indicated change in the crystalline features of the polymer in the case of CPE35 blends. The optical microscopy also confirmed the better mixing of CPE25 polymers in HDPE than CPE35. The CPE25 blends exhibited uniformly dispersed CPE phase which was also confirmed by the rheological analysis. However, the blends of CPE35 with 10% CPE content onwards had significant phase immiscibility. POLYM. ENG. SCI., 54:85–95, 2014. © 2013 Society of Plastics Engineers