This article focuses on the effect of mercapto additives on electroless pure copper thin film deposition. The copper deposits produced by the autocatalytic bath comprising xylitol, glyoxylic acid, and potassium hydroxide as complexing agents, reducing agents, and pH adjusters, respectively, were of superior grade. pH 13.0 ± 0.25 and 45°C were ideal bathing conditions. In order to improve the thermal stability and the good take hold off with copper, a trace quantity of methanesulphonic acid was used. Nitrogen and sulphur containing heterocyclic compounds such as 2-mercaptopyridine and 2-mercaptopyrimidine were used as the bath stabilizers. 1 ppm of the mercapto stabilizers stabilizes the bath conditions and their inhibiting potential was studied. The influence of the fundamental bath parameters on autocatalytic pure copper deposition have been investigated in our study. Physical properties and stability were characterized by the gravimetric method. The diffraction method was used to examine the structural characteristics of the copper deposits.