The argon temperature and the emission intensity in the hollow cathode discharge were measured. We measured the line profiles of the 1s 5 -2p 8 transition in argon, using a single-frequency diode laser. Low power diode lasers have been used to investigate the line profiles of argon transitions in hollow cathode discharges. It turns out that the argon temperature is 640-783 K in the discharge current range of 7.00-10.0 mA. The emission intensity is uniform in the negative glow at the current range over 5.00 mA under the pressure of 3.00 Torr.