The aim of this study was to assess the temperature response of photosynthesis in rubber trees (Hevea brasiliensis Mu¨ll. Arg.) to provide data for process-based growth modeling, and to test whether photosynthetic capacity and temperature response of photosynthesis acclimates to changes in ambient temperature. Net CO2 assimilation rate (A) was measured in rubber saplings grown in a nursery or in growth chambers at 18 and 28_C. The temperature response of A was measured from 9 to 45_C and the data were fitted to an empirical model. Photosynthetic capacity (maximal carboxylation rate, Vcmax, and maximal light driven electron flux, Jmax) of plants acclimated to 18 and 28_C were estimated by fitting a biochemical photosynthesis model to the CO2 response curves (A-Ci curves) at six temperatures: 15, 22, 28, 32, 36 and 40_C. The optimal temperature for A (Topt) was much lower in plants grown at 18_C compared to 28_C and nursery. Net CO2 assimilation rate at optimal temperature (Aopt), Vcmax and Jmax at a reference temperature of 25_C (Vcmax25 and Jmax25) as well as activation energy of Vcmax and Jmax (EaV and EaJ) decreased in individuals acclimated to 18_C. The optimal temperature for Vcmax and Jmax could not be clearly defined from our response curves, as they always were above 36_C and not far from 40_C. The ratio Jmax25/Vcmax25 was larger in plants acclimated to 18_C. Less nitrogen was present and photosynthetic nitrogen use efficiency (Vcmax25/Na) was smaller in leaves acclimated to 18_C. These results indicate that rubber saplings acclimated their photosynthetic characteristics in response to growth temperature, and that higher temperatures resulted in an enhanced photosynthetic capacity in the leaves, as well as larger activation energy for photosynthesis.