In order to prevent hazardous contamination inside satellite stations by the sediment action of frozen toxic liquid propellant on the space suits of astronauts, it is necessary to understand the phase changes of the leaked liquid propellant in case of valve breakdown. Using MON-3 as the liquid propellant, the minimum flow rate of MON-3 released without freezing to the vacuum chamber was investigated. For all the experimental flow rates tested in this study (0.347X 10(-5)-4.45 X 10(-5) g/s), MON-3 was found to freeze when released into the vacuum chamber. Freezing may be caused by the loss of latent heat to the surroundings in the vicinity of the orifice outlet where vaporization occurs.