One-, three-, and seven-layer Langmuir-Blodgett (LB) films of a mixed-stack charge-transfer (CT) complex of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (C(18)TCNQ) and N,N,N',N'-tetramethylbenzidine (N-TMB) were successfully deposited onto CaF2 plates and gold-evaporated glass slides at the surface pressure of 10 mN m(-1). This is the first time that the mixed-stack CT films of N-TMB . C(18)TCNQ have been prepared by the LB technique. Ultraviolet-visible-near-infrared (UV-vis-NIR) and infrared spectroscopies have been employed to investigate the formation, degree of charge transfer, molecular orientation, and structure of the CT complex in the LB films. The appearance of a broad absorption band with its center at about 1750 nm reveals that the CT complex in the LB films is in the mixed-stack form. The frequency of a C=N stretching band of C(18)TCNQ in the CT complex indicates that the degree of charge transfer (rho) is about 0.24. A comparison of the infrared band intensities between the transmission and RA spectra suggests that the chromophore planes for both C(18)TCNQ and N-TMB are nearly parallel to the substrate surface in the CT LB films. This result is in a good agreement with the requirement for the formation of the mixed-stack complex in which the donor and acceptor components should be in a face-to-face contact with each other. The hydrocarbon chain of C(18)TCNQ is considerably tilted with respect to the substrate normal in the CT LB films. The CT film (LB-doping film) of N-TMB . C(18)TCNQ was also prepared by LB- and donor-doping techniques. It was found that N-TMB . C(18)TCNQ molecules are partly dissolved in the petroleum ether solution during the doping procedure.