  Methyl vinyl ketone (C$_4$H$_6$O) 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 \emph{s-cis} and \emph{s-trans} conformers of methyl
vinyl ketone using the electrostatic deflector. The resulting sample density
was $1.5(2)\times10^{8}~\text{cm}^{-3}$ 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.
