High quality and intensely fluorescent Langmuir-Blodgett (LB) films of Eu(TTA)(3)Phen/AA (in molar ratio 1:1) (AA, arachidic acid) and Sm(TTA)(3)Phen/AA (1:1) were fabricated successfully by using the composite subphase that, here, denotes the aqueous solution saturated with Phen (1,10-phenanthroline), TTA (alpha-thenoyltrifluoracetone) and Eu(TTA)(3)Phen or Sm(TTA)(3)Phen. FTIR results indicate that hydrogen bonds form between -CF3 of the title complexes and -COOH of AA in these LB films, Low-angle X-ray diffraction results show that these LB films all have a periodic layer structure. The vertical uniformity of these LB films has been demonstrated by UV-Vis spectra and fluorescence emission spectra. Both absorbance and relative fluorescence intensity increase linearly with the number of LB layers. The two LB films can give off strong fluorescence, even though only one layer of LB film gives off strong fluorescence on ultraviolet irradiation. Strong fluorescence emission can be detected from this LB film by using a fluorescence spectrophotometer. Bright fluorescence spots can also be observed within the view field of a fluorescence microscope. However, when comparing one with the other, the fluorescence intensity of Eu(TTA)(3)Phen LB films is stronger than that of Sm(TTA)(3)Phen LB films. The intensity of the former is nearly 25 times the intensity of the latter.