N-(S-sodium propylsulfonate)-alpha-naphthylamine-formal condensates (NAFS) and O-(3-propylsulfonate)-alpha-naphthol-formald condensates (NOFS) are synthesized by condensation reactions followed by ring-opening reactions. Those condensates are used as dispersants to disperse dyes in water (C.I. Navy Blue 79 and C.I. Brown 1), and can be compared to the conventional dispersants [e.g., naphthalenesulfonate-formaldehyde condensates (NSF)]. The dispersing properties of the condensates were evaluated by scanning electron microscopy (SEM), sedimentation, as well as measurments of viscosity. For NAFS or NOFS, the sulfonate groups were grafted separately on the backbone of the condensate; however, for NSF, the sulfonate groups were anchored on the backbone of the condensate. The structural effects of those condensates were demonstrated by comparing the dispersing ability of these condensates, and the conventional condensates NAFS and NOFS exhibit better dispersing abilities than NSF for the Navy Blue 79 and Brown 1 dyes.