In growth of single crystal silicon by the Czochralski technique, it is important to know the actual value of the oxygen dissolution rate from silica glass to silicon melt at the triple-junction point of solid (silica glass)/liquid (silicon melt)/gas (argon). For the purpose of determining this value, a numerical simulation model was developed for the sessile drop experiment. In order to satisfy the presence of oxygen concentration along the melt/gas interface, a new interface condition was introduced in the model. Numerical simulation results are in good agreement with experiments. The values of oxygen dissolution rate at the condition corresponding to the triple-junction point (a very small drop that is not possible to form experimentally) were computed. The computed value at this point is about two times larger than the experimentally measurable value by the sessile drop method. (C) 2002 The Electrochemical Society.