An electron diffraction investigation of 1-methoxycyclohexene was undertaken to determine if the molecule possesses a favored conformation for the vinyl ether portion. In the gas phase, the molecule was found to be predominantly, if not entirely, in the cis conformation. In the cyclohexene ring, the bonded parameters are found to be C=C=1.333± 0.009 A (lC=C=0.048± 0.007 A), C2–C3=1.503± 0.006 A (lC–C=0.051± 0.005 A), C3–C4=1.514± 0.006 A (lC–C=0.042± 0.005 A), C4–C5=1.539± 0.014 A (lC–C=0.041± 0.009 A), the single bonds becoming longer the larger the separation from the double bond. The bonded parameters associated with the methoxy group are C–O=1.364± 0.006 A (lC–O=0.039± 0.005 A) for the distance from the ring to the carbon atom and C–O=1.421± 0.006 A (lC–O=0.041± 0.005 A) for the distance from the oxygen atom to the methyl carbon atom. The ring angles are C6C1C2=124.2± 1.0°, C1C2C3=123.1± 1.0°, C2C3C4=112.1± 1.0°, C3C4C5=111.5± 1.0°. The angles associated with the methoxy group are OC1C2=122.5± 1.5°, C6C1O=113.3± 1.5°, C1OC7=119.7 ± 2.5°. The methoxy group is attached at C1 and the double bond is formed between C1 and C2. The distances are rg values and the errors are limits of error at a confidence level of 95%.