Methyl vinyl ketone (C4H6O) is a volatile, labile organic compound of importance in atmospheric chemistry. We prepared a molecular beam of methyl vinyl ketone with a rotational temperature of 1.2(2) K and demonstrated the spatial separation of the s-cis and s-trans conformers of methyl vinyl ketone using the electrostatic deflector. The resulting sample density was 1.5(2) x 10(8) cm(-1) for the direct beam in the laser ionization region. These conformer-selected methyl vinyl ketone samples are well suited for conformer-specific chemical reactivity studies such as in Diels-Alder cycloaddition reactions.