A Pt/H-mordenite (Pt/H-MOR) Catalyst has been modified with tin using the controlled surface reaction between tin tetraalklyls and hydrogen adsorbed on platinum. Experimental evidences show that upon modification of Pt/H-MOR catalyst with tin tetraalkyls, the surface chemistry established for Pt/SiO2 and Pt/Al2O3 cannot be maintained, i.e., the formation of multilayered organometallic complexes (MLOC) is hindered. Consequently, the results indicate that the introduction of tin into platinum is possible if the Sn/Pt-s ratio is below 0.5. In this case, zeolite supported alloy type Sn-Pt nanoparticles are formed. At higher Sn/Pt-s ratios, in addition to the formation of alloy type Sn-Pt nanoparticles, ionic forms of tin anchored onto the zeolite are also formed. The reaction between tin tetraalkyls and surface OH groups of the zeolite is involved in the formation of ionic forms of tin stabilized an the zeolite surface. Upon applying Mossbauer spectroscopy, different tin containing surface species were identified including two SnPt alloy phases. Tin introduced in this way slightly decreases the H/Pt and CO/Pt ratios measured by chemisorption and changes the activity and selectivity of these catalysts in n-hexane isomerization at 275 degreesC,