Five stable conformations of the 1,1-dicarboxycyclobutane molecule were found based on the DFT calculations at the B3PW91/6-311++G∗∗ level. In order to model interactions in crystal phase, the most stable conformer was simulated to be hydrogen bonded with two formic acid molecules and for such a system the theoretical IR spectrum was calculated and compared with that obtained experimentally for the crystalline phase. The structure and IR spectrum of the model system exhibit plausible agreement with the experimental crystal phase geometry and spectra.