Electrochemical measurements have been carried out for three sets of compounds. Set 1 comprising fourteen 4-(4-substitutedphenyl)-1-(isomericpyridoyl)thiosemicarbazides, Set 2 compri-sing three isomeric pyridine carboxylic acid hydrazides and Set 3 comprising three isomeric pyridine carboxylic acids. In all these compounds substituents on phenyl group are bromo, chloro, fluoro, methyl and methoxy group. All these compounds were studied in non-aqueous solvent DMF at 293K using linear scan voltammetry (LSV) as measuring techniques. LSV reveals a single reversible peak for all compounds. Effects of substituents on halfwave potential (E1/2) values were explained on the basis of resonance and inductive effects. E1/2 values were used for the evaluation of solvation energies (S) and electron affinities (A). Moreover, correlations of energies of lowest unoccupied molecular orbitals (ELUMO) and Hammett constants (s) with halfwave potentials (E1/2) and electron affinities (A) were also studied.