The literature related to methanol-to-hydrocarbons (MTHC) technology over the past two decades has been reviewed, covering mainly the methanol-to-olefin (MTO) and methanol-to-gasoline (MTG) reactions. The work before around 1990 is briefly addressed, and the interested reader's attention is drawn to review papers published during the late 1980s summarizing the early work related to the methanol-to-hydrocarbons technology. This review focuses mainly on the chemistry and mechanism of those reactions including the catalysts involved and their behavior due to crystal size, pore architecture, acidity and reaction conditions, covering the time since around 1990. In a second review authored by F. Keil, the process related items of methanol-to-hydrocarbons technology will be summarized and discussed in the light of kinetic and reaction technology aspects.