Three cross-linking reagents (PVA, glycerol and glucose) have successfully been used to synthesize non-doped and metal-doped nanosized cryptomelane materials via a solid-state preparation method. The 2×2 tunnel structure of cryptomelane was formed at 500 °C. FT-IR data show that no cross-linking reagent residues were found in the products after the reactions were complete at 800 °C. The metal dopants used were Fe, Ag, Co, Cu, Ni, and Zn. XRD data show that Fe and Co cations can be doped into the materials without the formation of additional phases. The tunnel structures of the nanosized materials exhibit long-range along the b axis, as indicated by transmission electron microscopy data. High-resolution scanning electron microscopy studies show that morphologies of the products are nanorods or nanofibers, depending on the cross-linking reagents used in the preparation. Thermogravimetric analyses indicate that these nanomaterials are thermally stable to 700 °C.