By means of scanning tunnelling microscopy (STM) the nucleation, growth and sintering of platinum nanoparticles (Pt NP's) was studied on vicinal and flat rutile titanium dioxide (TiO₂) surfaces. Utilising physical vapour deposition, the nucleation of Pt NP's on TiO₂ surfaces at room temperature (RT) was found to be random and invariant towards different surface morphologies and reduction states. Thus, the nucleation of Pt on TiO₂ at RT is rather insensitive to the surface structure and surface defects. Vacuum-annealing at 600 K, 700 K and 800 K, respectively, led to lower densities of Pt NP's as a result of sintering. Sintering occurred at different rates at the TiO₂ surfaces studied, indicating that the surface morphology and the amount of Ti³⁺ excess charge do have an influence on the particle stability. Observed changes in the NP distribution as a result of sintering can be explained inferring facile diffusion of Pt NP's along the [001] direction.