The electrodeposition phenomenon of octyl thiolate-stabilized gold nanoparticles with a 2.3 ( 0.5 nm core diameter modified with biferrocene-terminated alkanethiolates on their surface (Au n -BFc) has been investigated using cyclic voltammetry, STM and AFM morphological observation, and electrochemical quartz crystal microbalance (EQCM) of the deposited Au n -BFc film. Consecutive potential scans causing two-step oneelectron oxidation of the biferrocene units of Au n -BFc in CH 2 Cl 2 electrolyte solution produce the adhesive Au n -BFc film on electrode surface. The deposition rate is lower for the biferrocene derivative on one particle θ BFc with a smaller modification number and a kind of electrolyte anion: ClO 4 -∼ BF 4 -. PF 6 -. The STM and AFM images have revealed that the thickness of the Au n -BFc film grows gradually by increasing the number of cyclic scans, forming many monolayer-level domains with ca. 80 nm diameter of the assembled Au n -BFcs. The average interparticle spacing of neighboring Au n -BFcs in the film is 7.5 nm, which is longer than the estimated diameter of whole Au n -BFc species (5.9 nm). Analysis of boron in the film electrodeposited in Bu 4 NBF 4 -CH 2 Cl 2 by the prompt γ-ray neutron activation (PGA) method shows that the BF 4 -ion is incorporated in the film. EQCM measurement suggests that not only ions but also the included CH 2 Cl 2 solvent molecules in the film are moved in and out reversibly in a potential range of E 0 ′ 2 of Au n -BFc. These results indicate that the formation of ionic lattice including Au n -BFc 2+ and counterion is accompanied by the exclusion of CH 2 Cl 2 solvent molecules among the particles in the initial deposition process.