Methyl tert-butyl ether (MTBE) is an organic compound. It appears as a colorless, transparent, low-viscosity liquid with a characteristic ethereal odor. It is highly flammable; its vapor is heavier than air and can spread at low levels. As an oxygen-containing organic ether (18.2% oxygen content) with a high octane number, it has stable chemical properties.

1. As a gasoline additive: Its primary application. It increases octane rating, improves anti-knock performance, promotes complete combustion, and reduces exhaust CO emissions.
2. As a chemical solvent: Used in extraction, chromatographic analysis, and as a solvent for organic synthesis.
3. As a feedstock for isobutylene: Cracked to produce high-purity isobutylene.