The results of an experimental study of wave motion on a falling liquid films over a range of film flow Reynolds number 10 < Re < 100 using liquids with various physical properties are presented. In the present study field optical measurement techniques such as shadowgraphy and high speed laser induced fluorescence method were used. Rivulets formation during the process of transition from two-dimensional to three-dimensional wave flow of the isothermal liquid films over a wide range of flow parameters was shown. Revealed rivulet nature of the liquid film flow can significantly affects heat and mass transfer processes in liquid films and should be taken into account while modeling such kind of a flow.