The effect of substrate temperature, 390-480 °C, during molecular beam epitaxy growth of InAsN quantum dots has been studied. The quantum dot formation was studied in situ, and it is shown that the quantum dots are close to fully relaxed within 4 monolayers (ML) of InAsN deposition. Further, the indium concentration was estimated to be 84%, 67%, 55% and 31% for 4 ML thick quantum dots grown at 390, 420, 450 and 480 °C, respectively. Thus, Ga incorporation was demonstrated at all substrate temperatures. The dot diameter and height increased from 23 to 38 nm, and 2.5 to 8.9 nm, respectively, when the growth temperature was increased from 390 to 480 °C. The 5 K photoluminescence intensity and wavelength both increased with substrate temperature.