The U.V. spectra of a series of cinnamylidene (mono and di-substituted) anilines have been studied in CCl4 with the shift reagent Ag(fod). A splitting of the main band into two bands was observed, which may be attributed to the complex formation with the Ag(fod). The equilibrium constant for the process was calculated using the method of Hartman. The U.V. spectra were measured at different temperatures (293-333 0K), the results showed a decrease in K values with increasing temperature. The thermodynamic parameters (AG, AH and AS) were obtained. Application of Skalski method showed that the interaction with Ag(fod) was 1:1.