Total vapor pressure data have been measured for the binary mixture methanol + 1,3,5-trioxane at 338, 343, 348, 353, 358, 363, and 368 K. The solubility of solid trioxane in methanol was determined from 293 to 328 K. The experimental data have been correlated using the UNIQUAC equation for the activity coefficient. In addition, the isobaric vapor-liquid equilibrium calculated predictions with the obtained parameters show good agreement with the experimental data available in the literature.