Objective:To investigate the influence of two new generations of light-emitting diode (LED) curing lights with different curing modes on the temperature rise in resin composite samples during their polymerisation. Methods: Bluephase C8 and Bluephase 16i (Ivoclar Vivadent) LED curing units with different curing programmes (high intensity programme [HIGH], low intensity programme [LOW], and soft-start programme [SOF]) were used for two types of resin composite polymerisation (Tetric Ceram, Tetric EvoCeram; Ivoclar Vivadent). The temperature was measured and recorded at the beginning and at the end of illumination using the ELV Pyroscan (ELV Elektronik) thermometer. Results: Regardless of the resin composite material used, there was a statistically significant difference between the temperature rise in polymerisation with Bluephase C8 and Bluephase 16i LED curing lights under the LOW programme (P = 0.022) and SOF programme (P = 0.033). However, no statistically significant difference was found in polymerisation with Bluephase C8 and Bluephase 16i LED curing lights under the HIGH polymerisation programme. Conclusion: Results from this study showed that the polymerisation programme, not the type of curing light used, was related to the rise in temperature. Keywords: LED curing unit, polymerisation curing mode, temperature