The formation of mixed-stack charge-transfer (CT) films was studied. Spectroscopic analysis suggested that donor doping to a 2-octadecyl-7,7,8,8-tetracyanoquinodimethan (C(18)TCNQ) film prepared by the Langmuir-Blodgett technique resulted in the formation of the mixed-stack CT him when 3,3’,5,5’-tetramethylbenzidine (TMB) was used as a donor, while degradation of the CT complex was observed when N,N,N’,N’-tetramethyl-p-phenylenediamine was used. Although X-ray diffraction measurements suggested that the order of the layered structure and crystallinity of the film were decreased by the doping, it was proved that the molecular columns of TMB and C(18)TCNQ were preferentially oriented along a substrate from polarized electronic spectra and scanning electron microscope observation. Therefore, non-linear electrical conduction as observed in mixed-stack CT crystals was expected. In the current density-electric field characteristic for the TMB-C(18)TCNQ film, the non-linearity was weaker than that observed in a TMB-TCNQ crystal. Furthermore, a temperature-induced neutral-ionic (N-I) phase transition was not observed from 4.2 K to room temperature in a spectroscopic measurement.