A compound of Formula (1) or a salt thereof useful as colorants for use in ink jet printing inks: wherein: A1 is optionally substituted phenyl; A2 is optionally substituted aryl; Q1 and Q2 are each independently an optionally substituted phenylene ring which is para connected to the —N═N— and the —NR— groups shown in Formula (1); and each R independently is H or a substituent; with the provisos that: (i) the compound of Formula (1) has at least one group selected from —SO3H and —PO3H2 groups; (ii) the compound of Formula (1) has more groups selected from —SO3H and —PO3H2 groups than the total number of —CO2H and —COSH groups; and (iii) the compound of Formula (1) is not of Formula (1a):