We describe the facile preparation of conductive casting films consisting of a mixed-valence 7,7,8,8-tetracyanoquinodimethane (TCNQ). Series of sterically hindered tertiary amines having polar groups such as ester or amide groups, i.e. N-hexyl-, N-octyl-, N-dodecyl-N,N-bis[2-(methoxycarbonyl)ethyl]amine (1, 2, and 3, respectively) and N-hexyl-N,N-bis[2-(hexylcarbamoyl)ethyl]amine (4), were applied for the charge-transfer reaction with TCNQ. We found that dark blue fiber-like TCNQ stacks in mixed-valence states were obtained after casting the acetonitrile solution of TCNQ with 1 or 2 on a Si substrate. In the case of using 3 or 4, however, no fiber-like TCNQ stacks but amorphous character films were obtained after casting the acetonitrile solution with TCNQ. We also found that the reversible thermophase transition temperature of the mixed-valence state TCNQ to the TCNQ anion radical can be tuned by changing the structures of the tertiary amines.