A nine-tray distillation column has been used to critically examine a constant-temperature region near the ternary homogeneous azeotrope in the system ethyl acetate-ethanol-water. Liquid samples withdrawn from the trays show an almost constant ethanol composition for a specific charge to the reboiler. An examination of the experimental discrete distillation lines on a portion of the ternary phase diagram showed that the constant-temperature region had been covered and an indication of a different location of the ternary homogeneous azeotrope. Process simulation studies could be expected to be difficult with existing parameters in thermodynamic models, under these conditions.