In this work, the optimization of phenolic compounds extraction from Eucalyptus camaldulensis leaves was carried out by applying a response surface methodology (RSM) approach. The influence of different parameters i.e., the liquid-to-solid ratio, the temperature and the extraction time have been jointly tested by maceration in an ethanol–water (70/30; v/v) mixture. A central composite design composed of 20 experimental trials with 6 replicates in the center was applied. A second-order polynomial model was used to describe the experimental data related to the extraction yield, the Total Phenolic Content (TPC), the total content of the major flavonoid compounds identified and quantified by high performance liquid chromatography–electrospray ionization mass spectrometry (HPLC–ESI–MS), and antioxidant activity by DPPH (2,2-diphenyl-l-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays. The optimum extraction conditions obtained were 12.4 mL/g, 50.4 °C, and 124.8 min, for liquid/solid ratio, temperature and contact time, respectively. Under these conditions, the predicted phenolic compound content was 342.8 ± 11.1 mg GAE/g dry extract. Analysis of variance (ANOVA) showed a good fit (p 

Eucalyptus camaldulensis, RSM, Optimization, Phenolic compounds, LC-MS analysis