The absorption spectrum of the KAr molecule has been observed with high resolution between 13 032 and 13 077 cm −1 using tunable laser diodes as light sources, a supersonic beam for production of the molecules, and laser-induced fluorescence for detection. In addition, optical–optical double resonance (OODR) experiments have been performed to simplify the spectrum and to get rotational assignment. Altogether, 670 lines due to the transition B 2Σ + ← X 2Σ + have successfully been assigned with vibrational levels of the B state ranging from v = 0 to v = 6. The corresponding energy values were fitted to the well-known Dunham expansion. In addition, we were able to analyse a local perturbation between the vibrational level v = 1 of the B state and v = 14 of the A 2Π 3/2 state. Unexpected extra lines in the OODR spectra are most probably due to a collision-induced population of other levels. For the equilibrium distance and the well-depth of the B state we obtain from the Dunham expansion 7.03 (8) Å and 26.2 (8) cm −1, respectively.