We present a study of bars in lenticular galaxies based on a sample of 371 galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) and Two-Micron All-Sky Survey in the optical and near-infrared bands, respectively. We found a bar in 15 per cent of the lenticular galaxies in our sample, which is consistent with recent studies. The barred galaxy fraction shows a luminosity dependence, with faint lenticular galaxies (MK > −24.5, total absolute magnitude in the K band) having a larger fraction of bars than bright lenticular galaxies (MK < −24.5). A similar trend is seen when Mr=−21.5, the total absolute magnitude in the SDSS r band, is used to divide the sample into faint and bright lenticular galaxies. We find that faint galaxies in clusters show a higher bar fraction than their counterparts in the field. This suggests that the formation of bars in lenticular galaxies not only depends on the total luminosity of the galaxy, but also depends on the environment of the host galaxy.