Matrix IR and Raman spectra of CF3Cl and CF3Br with natural abundance of halogen and C and 90% 13C enrichment were recorded at 200-2500 cm-1. A harmonic force field for CF3Cl was obtained and a force field transfer was applied to CF3Br. The CF and CX stretching force consts. were 6.75 and 3.60 mdyne/.ANG. for CF3Cl and 6.46 and 2.91 mdyne/.ANG. for CF3Br.