In this article, a modified version of the gradient-corrected BP86 functional is presented. Such a functional, called mBP86, has been obtained by a reparameterization of the Becke's 1988 exchange functional on the activation barriers of selected proton transfer reactions. Whereas standard GGA methods usually underestimate these values, the mBP86 model shows a significant improvement. As a "side effect", several other chemical properties, including atomization and reaction energies, are also better described and are included so that the mBP86 can be considered to be a general improvement over the parent BP86 functional. Next, the proposed approach has been used to simulate proton transfer reaction in malonaldehyde and in the protonated imidazole dimer by first-principles Molecular dynamics. These Simulations indicate that this modified functional provides energy and structure evolution very close to the Popular B3LYP functional. More generally, Our results suggest that the mBP86 can be a cheap, yet reliable, alternative for large scale simulation of proton transfer carried out using approaches where the popular hybrid functionals cannot easily be routinely used.