The production of oxygen carriers is currently a topic of paramount interest in nanotechnology. Particularly, there is a focus in the development of microparticles with round and uniform shapes to further expand their potentialities. Here, we prepare homogenous microspheres with diameters of similar to 3 pm using porous calcium carbonate spheres as the template and glutaraldehyde as the cross-linking agent. Also, we present for the first time the use of electrochemical avenue to evaluate the oxygen-carrying ability of these as-prepared samples. Our results demonstrate successful construction of prospective microspheres which perform extraordinary oxygen-carrying capability with protection of bovine serum albumin layer on the surface. (C) 2016 Published by Elsevier B.V.