Lithiophorite[(Al, Li)MnO2(OH)2] is the main component of natural gosu, which is produced in Seto area, and utilized as ceramic pigment. In the present work, lithiophorite containing Co ion was hydrothermally synthesized, and the extent of Co content in lithiophorite was examined. Synthetic lithiophorite was better crystallized than natural product. Synthetic lithiophorite containing Co ion consisted of platelike particles with the grain size about 0.2μm and the thickness 150-200Å. It was revealed by the energy dispersion spectroscopy that Co was substituted for Mn continuously up to about 37.8atom%[Co/(Co+Mn)]. However, the increase of Co content in the starting material resulted in the coprecipitation of spinel type by-product Co(Al, Mn, Co)2O4. In conclusion, synthetic lithiophorite containing Co ion showed well powder and coloring characteristics as ceramic pigment.