A novel solid-liquid reaction route has been developed to synthesize rodlike submicron cobalt oxalate via dissolution of cobalt powders by oxalic acid. The rod diameter and length of the oxalate particles were found to be remarkably altered by using HCl or HNO3 as additive. With HCl as additive rice-shaped particles were generated while with HNO3 slender needlelike particles were created with an average aspect ratio up to 42. Furthermore, strings of Co3O4 nanobeads were obtained by calcination of the slender precursor particles in air. The CoC2O4·2H2O submicron rods and Co3O4 nanobeads were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TG), and X-ray diffraction (XRD).