The microwave spectra of 2-cyclopropylideneethanol, (CH(2))(2)C=C-CH(2)OH, and one deuterated species (hydroxyl group) have been investigated in the 23.0-39.0 GHz spectral region at 263 K. One conformer, denoted Skew I, was assigned. In this rotamer the C=C-C-O dihedral angle is 122 degrees from syn (0 degrees) and the C-C-O-H dihedral angle is 66 degrees from syn. The hydrogen atom of the hydroxyl group forms a weak intramolecular hydrogen bond with the pi electrons of the C=C double bond. The gas-phase IR spectrum in the OH stretching region revealed a broad and complex band at a rather high wavenumber. This absorption split into three bands, presumed to belong to two conformers with an internal hydrogen bond and one without, when the compound was isolated in argon matrices at 5 K. Large shifts were observed between the IR spectra of the amorphous and crystalline solids at liquid nitrogen temperature due to hydrogen bonding. Certain weak IR and Raman bands present in the amorphous or liquid phases vanished in the crystal and are attributed to one or more additional conformers in the liquid. Some IR bands in the range 3670-3630 cm(-1), present in the argon matrix spectra at 5 K of a ca. 550 K vapour deposit, vanished after annealing and were tentatively attributed to high energy conformers. From temperature variations in the Raman spectra of the liquid Skew 1 was estimated to be 2.5+/-0.6kJ mol(-1) lower in enthalpy than other conformations. The experimental work has been assisted by ab initio computations at the MP2/6-31G** level of theory.