In Brazil, Eucalyptus plantations have been established in soils subjected to drought periods. Potassium has an important role in plant capacity for tolerating low water availability. Pots experiments are well controlled and allow the prediction of results under field conditions. This study aimed to evaluate the effects of different potassium rates and water stress levels on morphological and physiological characteristics of Corymbia citriodora (Hook.) K. D. Hill & L. A. S. Johnson plants. Plants at 28 cm height were put into pots which contained 5 dm³ Red Latosol. Fertilizer doses used 0, 40, 80 and 120 mg dm^-3 K₂O and the humidity levels promoted were 50-80%, 65-80% and 80% field capacity. At 60 days after the potting, the plants were under mild (50-80%) and severe stress (65-80%) had reduced height growth in comparison to well-watered ones. High potassium levels decreased stomatal conductance but they did not affect the photosynthesis rate. The experiment results suggested that C. citriodora young plants have better development with 40 mg dm^-3 K₂O application and field capacity between 70 and 80% depending on the analyzed characteristic.