We present evidence for 130 nm thick pentacene films ordered in the orthorhombic phase obtained by iodine diffusion into the film deposited by classical thermal evaporation. After desorption of iodine by vacuum annealing the crystallographic properties of the investigated pentacene films resemble those of very thin thermal evaporated films that exhibit an orthorhombic phase with high electrical performance. Therefore, the results presented in this work are believed to be important for the development of organic field-effect transistors. (C) 2009 Elsevier B. V. All rights reserved.