The products of vaporization of boron/carbon mixtures around 3000 K were trapped in argon matrices at 10 K and their Fourier transform infrared spectra were measured. Analysis of the spectra combined with the predictions of density functional theory (DFT) calculations have resulted in the assignment of a previously observed vibration at 1194.4 cm(-1) to the nu(2) fundamental of cyclic BC2, which is effectively symmetric. The assignment is supported by B-10, B-11, and C-13 isotopic data and is in good agreement with the theoretical predictions.