Cobalt oxyhydroxide nanocrystals were synthesized in an aqueous solution in the cavity of the apoferritin from horse spleen (HsAFr), and two-dimensional CoOOH-ferritin nanodots were prepared by simple touch method on modified silicon surface. In the synthesis, CoOOH nanocrystals are encapsulated and growth is restricted to the internal dimension of the protein cavity. The obtained nanodots were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), absorption and photoluminescence (PL) measurements. From the results, it was concluded that CoOOH nanocrystals were successfully synthesized in the core of ferritin and the monolayer of CoOOH-ferritin could be obtained on the surface of modified silicon surface. In addition, CoOOH quantum dots(QDs) in ferritin core provided the PL emission peak. Accordingly, the CoOOH-ferritin arrays can be employed as a potential useful biosensor material for PL technique.