Dew points of pure 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were measured using low pressure distillation. The distillation experiments were conducted within a 0.5-12.1 kPa pressure range. The measured dew point data were in good agreement with the vapor pressure data available in the open literature. The combined measured dew point and literature vapor pressure data were modeled using an Antoine type equation. Vapor-liquid equilibrium (VLE) of water + DBN and water + DBU systems were measured using two variations of a static total pressure method. The VLE measurements were conducted within a 313-353 K temperature range. The results indicate a negative deviation from Raoult's law for both systems. Legendre polynomial and NRTL activity coefficient models were used to describe the liquid phases of the systems. (C) 2015 Elsevier B.V. All rights reserved.