Conversion of methanol with HI additive to olefins (IMTO) over SAPO-34 catalyst was investigated at various temperatures. The SAPO-34 catalyst showed high olefin selectivity and methanol conversion for the IMTO process. Comparative experiments were performed to investigate the effect of the HI additive on the product distribution. The methanol conversion increased after HI was added into the feedstock. The reaction temperature for the maximum selectivity of light olefins was 100 K lower than that for the methanol-to olefin (MTO) process. The used SAPO-34 catalyst after the IMTO reaction and the fresh catalyst were both characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectrometry to investigate the effect of the HI additive on the properties of SAPO-34. The CHA structure of SAPO-34 was not destroyed by the HI additive, whereas the morphology and size of the crystals changed. In addition, a comprehensive thermodynamic analysis of overall reaction network was performed to address the major channels and explore the dependence of the product composition on the reaction temperature. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.