Disclosed is an ink composition which comprises an aqueous liquid vehicle, a colorant, and an additive material selected from the group consisting of (a) symmetric acetylenic bisester alcohols, (b) symmetric acetylenic bisalkyl alcohols and acetylenic bisalkoxy alcohols, (c) symmetric acetylenic bisamido alcohols, (d) symmetric bisamido alcohols, (e) mono amido alcohols, (f) trialkylhydroxy compounds, (g) derivatives of 1,2-diols and 1,3-diols, (h) thio diols, (i) aromatic diols, (j) heterocyclic diols, (k) imino alcohols, (l) salts of hydroxyl compounds, (m) saccharides and saccharide derivatives, and (n) mixtures thereof. Also disclosed is an ink jet process which comprises (1) incorporating into a thermal ink jet printing apparatus the aforementioned ink composition; and (2) causing droplets of the ink to be ejected from the printing apparatus in an imagewise pattern onto a substrate, thereby generating images on the substrate. Further disclosed is an ink jet printing process which comprises (1) incorporating into a thermal ink jet printing apparatus the aforementioned ink composition; (2) causing droplets of the ink to be ejected from the printing apparatus in an imagewise pattern onto a substrate, thereby generating images on the substrate; and (3) exposing the substrate to microwave radiation, thereby drying the images on the substrate.