The Sparkle model, recently defined for Tm(III) within AMI [R.O. Freire, G.B. Rocha, A.M. Simas, Chem. Phys. Lett. 411 (2005) 61], is now extended to PM3. For the same 15 complexes previously used, the Sparkle/PM3 unsigned mean error, for all interatomic distances between the Tm(III) ion and the directly coordinating oxygen or nitrogen atoms, is 0.08 angstrom, a level of accuracy equivalent to the Sparkle/AM1 figure of 0.07 angstrom, as well as to results from present day ab initio effective core potential calculations. The results thus indicate that both Sparkle/AM1 and Sparkle/PM3 models may prove useful for luminescent Tm(III) complex design. (c) 2006 Elsevier B.V. All rights reserved.