Crystals of Tl 1 . 3 Hg 0 . 7 Ba 2 CaCu 2 O 8 (TlHg-2212) and Tl 1 . 6 Hg 0 . 4 Ba 2 Ca 2 Cu 3 O 1 0 (TlHG-2223) phases with T c =110 and 120 K have been grown by a self-flux method in sealed silica tubes. The structural characterizations performed by means of X-ray single crystal data and electron microscopy (diffraction and high resolution) demonstrate that the 2212 and 2223 structures are unchanged by the substitution of Hg for Tl. Few defects have been observed in the case of the TlHg-2212 single crystals; they consist in the introduction of additional [CaCuO 2 ] ~ layers that can lead locally to the formation of 1223 like structures. The doping level of these crystals is similar to that of the Tl pure 2212 and 2223 crystals. Consequently, the superconducting properties are not affected by the Hg introduction. The surfaces quality and the shapes regularity of these new crystals offer new interesting candidates for the transport measurements of high T c superconductors (HTCS) as shown from ρ c resistivity curves.