Under controlled conditions of food density and temperature, larval performances (ingestion, growth, survival and settlement success) of the flat oyster, Ostrea edulis, were investigated using a flow-through rearing system. In the first experiment, oyster larvae were reared at five different phytoplankton densities (70, 500, 1500, 2500 and 3500 μm3 μL−1: ≈1, 8, 25, 42 and 58 cells μL−1 equivalent TCg), and in the second, larvae were grown at four different temperatures (15, 20, 25 and 30°C). Overall, larvae survived a wide range of food density and temperature, with high survival recorded at the end of the experiments. Microalgae concentration and temperature both impacted significantly larval development and settlement success. A mixed diet of Chaetoceros neogracile and Tisochrysis lutea (1:1 cell volume) maintained throughout the whole larval life at a concentration of 1500 μm3 μL−1 allowed the best larval development of O. edulis at 25°C with high survival (98%), good growth (16 μm day−1) and high settlement success (68%). In addition, optimum larval development (survival ≥97%; growth ≥17 μm day−1) and settlement (≥78%) were achieved at 25 and 30°C, at microalgae concentrations of 1500 μm3 μL−1. In contrast, temperature of 20°C led to lower development (≤10 μm day−1) and weaker settlement (≤27%), whereas at 15°C, no settlement occurred. The design experiments allowed the estimation of the maximum surface-area-specific ingestion rate \J˙Xm\ = 120 ± 4 μm3 day−1 μm−2, the half saturation coefficient \XK\ = 537 ± 142 μm3 μL−1 and the Arrhenius temperature TA = 8355 K. This contribution put a tangible basis for a future O. edulis Dynamic Energy Budget (DEB) larval growth model.