Novel compounds, 4-alkyl-cyclohexenes having at the 1-position thereof p-cyanophenyl group or 4'-cyano-4-biphenylyl group, expressed by the general formula ##STR1## wherein R represents a straight alkyl group having 1.about.9 carbon atoms and n represents 1 or 2; methods for producing the same; and nematic liquid crystal (L.C.) compositions comprising at least one member selected from the group consisting of said compounds, are provided. Said compounds having a cyclohexene ring have a lower viscosity than conventional L.C. compounds, and have effectivenesses of short response time when applied to L.C. display apparatus; superior compatibility with other L.C. compounds to form convenient L.C. mixture; and no need of separating cis- and trans-forms in the midway step of the preparation as in the prior art.