This book deals Spectral investigations Inhibition efficiency and analysis of 5-chloro-2-nitroanisole as π-spacer with donor-acceptor variations effect for DSSCs performance.Furthermore the first hyperpolarizability of 5-chloro-2-nitroanisole was calculated and the results were discussed. This result indicates that 5-chloro-2-nitroanisole is a good candidate of nonlinear optical materials. The preferred active sites for the electrophilic and nucleophilic reactions are also identified by the Fukui indices of 5-chloro-2-nitroanisole.