We investigated the influence of the mixed n-alkanethiolate self-assembled monolayer (SAM) formed on gold nanoparticles (AuNPs: 50.0 +/- 3.2 nm in diameter) on their assembly into colloidal films. Dodecanethiol and octadecanethiol were selected as the short-and tong-chain alkanethiols, respectively. The mixed SAMs were formed by immersing AuNPs in a mixed alkanethiol solution at different molar ratios. Au colloidal films were fabricated on indium tin oxide substrates by our previously reported hybrid method. The composition of the two alkanethiolates in the SAM was deduced from the intensity ratio of two Raman bands at 1080 and 1105 cm(-1). The surface coverage of the colloidal films increased by forming equimolar Or dodecanethiolate-dominant mixed SAMS on AuNPs instead of a pure dodecanethiolate or octadecanethiolate SAM. The highest coverage exceeded 80%. This improvement is attributed to the high dispersion Stability of AuNPs covered with equimolar or dodecanethiolate-dominant mixed SAMs.