Zeolitic Imidazolate Frameworks (ZIFs) are porous materials which are known for their exceptional chemical/thermal stability and mostly hydrophobic character. These properties make them promising materials for use in the capture and/or detection of hazardous chemicals under humid environments. Henry's coefficient can be used in order to assess the affinity between a molecule and an adsorbent material. In this study, we used molecular simulations to find a suitable ZIF structure by a quick and easy screening method. For this screening method, the Henry's coefficients of one explosive (nitromethane), six toxic chemicals (hydrogen disulfide, sulfur dioxide, nitrogen dioxide, carbon monoxide, ethylene oxide, benzene), and three warfare agents (sarin, sulfurmustard, phosgene oxime) in pre-selected ZIFs according to their pore aperture size were computed. In addition, average loading values for the hazardous molecules under five different relative humidity conditions were obtained with GCMC simulations in ZIFs which gave the two highest Henry's coefficients with respect to the Henry coefficient of water. ZIF-1 and ZIF-68 were found to be the most promising materials for the majority of the hazardous chemicals considered in this study, with several orders of magnitude predicted preconcentration gains.