Highly selective catalytic oxidations of (sterically hindered) aryl thiophenes using stoichiometric amounts of hydrogen peroxide (35% in water) and cis-Ru(II) bis(substituted phenanthroline) complexes (as low as 0.1%) were carried out in acetonitrile at 75 degrees C, affording the corresponding sulfortes in high yields and selectivities. The products were recovered quantitatively by simple crystallization from the reaction mixture. (c) 2006 Elsevier B.V. All rights reserved.