The objective of the present study is to measure basal energy expenditure (BEE) using the Cosmed K4b2 portable metabolic system (Rome, Italy) and to develop a new predictive equation for BEE in southern Chinese adults. A total of 165 healthy Chinese adults aged 18–45 years with normal body weight were involved in the present study. BEE was measured by Cosmed K4b2. Body composition was determined by body composition analysers (ImpediMed DF50, QLD, Australia). Multiple linear regression analysis and correlation analysis were applied to develop a new optimal equation for predicting BEE of southern healthy Chinese adults. Measured BEE (mBEE) of southern Chinese healthy adults was 5513 (sem 96) kJ/d, which was similar to the results predicted by the equation developed by of Liu 5579 (sem 57) kJ/d (P = 0·37) and significantly lower than those from equations developed by Henry (5763 (sem 54) kJ/d), Schofield (5898 (sem 58) kJ/d) and Harris–Benedict (HB; 5863 (sem 51) kJ/d) (all P = 0·001). The optimal equation developed by our data was BEE (kJ/d) = 277+89 weight (kg)+600 sex (male = 1 and female = 0) (r2 = 0·48, n 165). For males, BEE (kJ/d) = 105 weight (kg) − 58 (r2 = 0·27, n 79); for females, BEE (kJ/d) = 69 weight (kg)+1335 (r2 = 0·24, n 86). In conclusion, the mBEE of southern Chinese healthy adults was 5513 (sem 96) kJ/d. The BMR of Chinese adults of normal weight is overestimated by widely used prediction equations developed by Henry, Schofield and HB. The equation developed in the present study (equation 7) can be used in predicting BEE for Chinese adults aged 18–45 years with normal body weight.