In this study, polyolefin blend type thermoplastic elastomer compounds were prepared via melt blending method in a twin screw extruder by using isotactic polypropylene (i-PP) as thermoplastic matrix, three different styrene-olefin triblock copolymers (SEBS-1 and SEBS-2 having styrene contents of 30 wt% and 60 wt%, respectively and SEEPS having a styrene content of 30 wt%) as elastomer phase and paraffinic oil as plasticizer. Microstructural, morphological, thermal, mechanical, and solid-state viscoelastic properties of compounds were investigated with SEM, XRD, DSC, DMA methods, and tensile tests depending on structural difference of elastomer phase and compositional variations. It was found that styrene content of elastomeric component govern physical properties of compounds and higher styrene content lead to increase immiscibility between thermoplastic and elastomer phases. It can be concluded that elastomer amount into composition dramatically affects the short-term mechanical properties of compounds such as elastic modulus, yield stress, and yield strain while elastomer type does not influence such properties, significantly. On the other hand, elastomer type, specifically hard segment content, possess a great effect on long-term physical performances of compounds. (C) 2018 Elsevier Ltd. All rights reserved.