We present the results of molecular dynamics simulations of Langmuir monolayers of a semifluorinated hydrocarbon molecule F(CF2)(12)(CH2)(18)H. Our simulations show that highly ordered structures can be formed at low temperature after quenching from a random structure at high temperature. The structural formation process of the monolayer is characterized by a decrease in the gauche defects of the hydrocarbon block and an increase in the global bond-orientational order throughout the chain molecules. The behavior of the order parameter exhibits a sudden change, signaling a structural phase transition. Structural formation of the semifluorinated monolayer is found to depend on temperature, suggesting that the time scale for the ordering process is determined by the rate of conformational change. It is also found that the monolayer structure consists of clusters of different chain orientations relative to the interface for the head-group-free F(CF2)(12)(CH2)(18)H molecule, with a slightly larger fraction for a hydrocarbon-down, fluorocarbon-up configuration.