We report measurements of the bulk, neutral gas temperature in a chlorine transformer-coupled plasma. A trace amount (2%–5%) of N2 was added to the discharge and the rotational temperature of the C3Πu state was determined from the C3Πu→B3Πg emission in the ultraviolet. This temperature has been shown by others to be equal to the rotational temperature of ground-state N2, which is the thermally equilibrated (translational and rotational) gas temperature (Tg). The gas temperature 3 cm above the wafer is equal to, or only slightly above the wall temperature (300 K) throughout the low-power, capacitively coupled regime (<60 W, 0.024 W/cm3). Between the lowest (130 W, 0.053 W/cm3) and highest (900 W, 0.36 W/cm3) inductively coupled mode powers investigated, Tg increases sublinearly with power (and electron density). The high-power (900 W) Tg increases with increasing pressure (650, 750, 900, and 1250 K at 2, 5, 10, and 20 mTorr, respectively). Mechanisms of neutral gas heating are discussed. The energy released in dissociation of Cl2 appears to be the dominant heating mechanism. © 2000 American Institute of Physics.