Thermal conditions in seven rock glaciers (RGs) in the Retezat Mountains were examined using ground surface temperature, the bottom temperature of snow (BTS) and late-summer water temperature at springs. Direct current resistivity profiles were used to detect ice-rich layers and to estimate RG volume. These parameters were supplemented by measurements of RG surface movement and morphological characteristics in order to develop a RG typology. RG activity is suggested based on BTS values and the mean annual surface temperature. The lower altitudinal limits for permafrost occurrence and the activity of RGs were found to be at 2000 m and 2100 m asl, respectively. The two highest and most active RGs are younger than 8 ka and developed following a cold climate event at 8.2 ka when a last isolated glacial episode occurred in their hosting cirques, while the remaining RGs date from 11.5–8.7 ka. Calculated rockwall denudation rates to produce these forms range from 0.8–1.1 mm/yr. Copyright © 2012 John Wiley & Sons, Ltd.