The possibility of reducing the toxicity of exhaust gases by using alternative types of motor fuel is examined. Diisopropyl ether (DIPE) is proposed as a promising high-octane additive. The properties of C-5-C-6 ethers are compared and the advantages of DIPE are noted: the broader feedstock base and replacement of methanol with water. The possibility of synthesizing DIPE from propylene and water on a new active catalyst with a yield of up to 90% in propylene is demonstrated. The use of DIPE as a promising replacement for MTBE is substantiated.