The WO molecule was formed as an impurity during the excitation of a mixture of WCl6 vapor and He in a microwave discharge lamp. The emission spectra were recorded using a high-resolution Fourier transform spectrometer. A rotational analysis of the strong bands in the 9000-25 000 cm(-1) interval has been carried out and the bands have been classified into two groups with different lower states. The two lower states have been assigned as the Ohm = 0(+) and Ohm = 1 spin components of the X(3)Sigma (-) ground state. Ab initio calculations have also been performed and they confirm our experimental assignments.