A new photoimaging system from poly(sodium styrene sulfonate) (PSS) and 3,3′-dimethoxy-diphenyl-4,4′-bisdiazonium salt (DDBS) in sodium dodecyl sulfate (SDS) aqueous solution has been developed. The water soluble components, that can be coated, become insoluble under UV irradiation. The dramatic change in the solubility of the coated film under exposure to UV light originates from the decomposition of the diazonium group of DDBS. As a result, the ionic bond of PSS-DDBS is converted to a covalent bond. It was confirmed that the SDS plays an important role in enhancing the thermal stability of PSS-DDBS both in solution and in coated film. A proposal to explain the increasing thermal stability of the PSS-DDBS in the presence of SDS has been proposed.