Solvent free and selective isomerization of p-diethylbenzene (p-DEB) to m-diethylbenzene (m-DEB) was carried out using metal modified zeolite Hβ at high temperature. The metal modification of Hβ catalyst was carried out by using typical Lewis acidic cations Al 3+ , Fe 3+ , Ti 4+ , Sn 4+ and Sb 3+ . The catalysts were characterized by XRD, FE-SEM, HR-TEM, FT-IR, N2-desorption (BET), ICP-AES, NH3-TPD, pyridine-IR, and TGA techniques for structure, morphology, acidity and stability. Particle size of the crystallites was determined by HR-TEM and the size was in the range of 15 - 35 nm. At 250oC, Al-Hβ, Fe-Hβ and Ti-Hβ catalysts showed 69 - 75% conversion of p-DEB with 43 - 51% selectivity towards m-DEB. This process is a greener alternative to the classical AlCl3 process. Further, such an isomerization would make the styrene manufacture more economic.