Photobase generator is recently attracting more attention because it is freed from oxygen inhibition and metal corrosion, compared to photoacid generator and photo radical generator. 2-(9-Oxoxanthen-2-yl)propionic acid (OXTA) has an absorption in the range of i-line wavelength and it can form a salt with phosphazene base (P 2 tBu). It is photobase generator (PBG) to generate an organic superbase efficiently by UV irradiation. In this study, we synthesized a series of salts of OXTA and P 2 tBu (OXTA-P 2 tBu) at several anion-cation ratio. Then, we analyzed the PBG with each ratio by pH, UV absorption and ESR, and calculated OXTA-P 2 tBu complex by (TD)B3LYP/6-31+G(d,p) level. The crystal of OXTA-P 2 tBu synthesized at optimum ratio was analyzed by single crystal X-ray diffraction and we described the crystal structure. Furthermore, we obtained nega-type pattern with polysilane solution containing OXTA-P 2 tBu in the optimum ratio.