Cesium dichromate forms triclinic crystals which are apparently isomorphous with potassium dichromate.1The only published x-ray study of this compound consists of powder pattern results2, and no determination of the space group has been presented. The only possible space groups for triclinic cesium dichromate are P1-C11and P1-C11, which are distinguished by the presence and absence of inversion symmetry, respectively. Since inversion symmetry precludes coincidence between the infrared and Raman spectra, vibrational spectroscopy may be applied to the determination of the space group. This approach has been used recently to verify the space group of potassium dichromate.3The present note presents the infrared and Raman spectra of crystalline cesium dichromate and our conclusions as to the space group.