Point contact tunneling studies have been done on an optimally-doped bi-layered cuprate TlBa2CaCu2O6.5+delta (Tl1212) with T-c similar to 109 K. The tunneling conductance curves display the d-wave superconducting gap with Delta similar to 31.1 +/- 7.1 meV. The statistical distribution of Delta shows the single-gap feature in contrast with that of TlBa2Ca2Cu3O8.5+delta (Tl1223) where two-gaps feature was observed. Moreover we observed the dip structures behind the gap peaks which would be due to the strong coupling structures. Based on the observed results, we found that Tl1212 is a d-wave strong coupling superconductor with 2 Delta/k(B)T(c) similar to 6.6. (C) 2010 Elsevier B.V. All rights reserved.