Topological indices are the numerical value associated with chemical constitution purporting for correlation of chemical structure with various physical properties, chemical reactivity or biological activity. Graph theory is a delightful playground for the exploration of proof techniques in Discrete Mathematics and its results have applications in many areas of sciences. One of the useful indices for examination of structure- property relationship is Randic' index. In this study is represented the relationship between the Randic', Balaban and Szeged indices and Harary numbers to the enthalpies of combustion ( liquid), enthalpies of vaporization( gas), enthalpies of formation ( liquid) and enthalpies of sublimation ( ) of monocarboxylic acids (C2- C20) are established, and then, some useful topological indices for examination of the structure- property relationship are presented.