Novel classes of ionic photoacid generator (PAGs) compounds having relatively environmentally friendly anions with no perfluorooctyl sulfonate (no-PFOS) are provided and photoresist composition that comprise such compounds. The new PAGs produce a photoacid having a short or no perfluoro alkyl chain (i.e., no-PFOS) attached to a variety of functional groups. The PAGs of the invention are useful as photoactive component in the chemically amplified resist compositions used for microfabrication.