CdS nanoparticles cast on the glassy carbon (GC) electrode was used to immobilize hemoglobin (Hb). The CdS nanoparticles could provide a favorable microenvironment for direct electron transfer between the electrode and the immobilized proteins. In addition, the immobilized Hb showed stable bioelectrocatalytic activity for the reduction of H2O2. CdS nanoparticles cast on the glassy carbon (GC) electrode was used to immobilize hemoglobin (Hb). The CdS nanoparticles could provide a favorable microenvironment for direct electron transfer between the electrode and the immobilized proteins. In addition, the immobilized Hb showed stable bioelectrocatalytic activity for the reduction of H2O2.