Polarographic study of Tl(I) complexes with L-Phenylalanine has been carried out in non-aqueous (20% ethanol, 40% ethanol) medium under varying temperatures 308 K and 318 K, in presence of KNO3 as supporting electrolyte. DeFord & Hume's method is used to calculate the stepwise formation constants. The reduction is found to be reversible and diffusion controlled involving one electron in each case. The complexes with metal to ligand ratio as 1 : 1, 1 : 2, 1 : 3 have been reported. The changes in thermodynamic parameters ΔH°, ΔG° and ΔS° accompanying complexation have been evaluated. The mathematical Mihailov's method has also been applied for the comparison of stability constants values.