PURPOSE: To obtain C.I. azoic diazo component aqueous liquid compound simply adjustable with ease of handling and capable of imparting excellent fastness to insoluble azo dyes by rendering the acid necessary for diazotization and dye coupling in the form of a nonvolatile acid in water vapor.

CONSTITUTION: (A) A aromatic diamine (C.I. azoic diazo component) or a salt thereof is stirred together with (B) an acid nonvolatile in water or water vapor (e.g. phosphoric acid) and, if necessary, (C) a dissolution accelerator and/or a dispersing agent is added thereto and, preferably, the mixture thus prepared is mixed into (D) a thickener containing sodium nitrite to obtain the objective aqueous compound.