Abstract: In the present investigation we have collected 60 sets of vertical ioniza-tion potentials of normal paraffins C_nH_2n+2 and other 19 sets of non-conjugated homologous series from UV photo electron spectroscopy and found to fit the following linear equation I_p(n,k)=a+bX(n,k) where I_P(n, k) is the kth ionization potential of the nth member of the homologous series, a and b are constants, X(n,k)is called the homologous energy factor and is equal to X(n,k)=[(2k-1)/k]sin(kπ/(2n+1)] 83.3% of the correlations are of the "excellent" grades with correlation factor r≥0.99, and 16.7% of the "good" grade with r≥0.95.