Amplitude-temporal and spectral paramters of laser radiation and electric discharge parameters in gas mixtures of SF6 with hydrogen and hydrocarbons in the high efficiency operation mode are studied. The laser effiency with respect to deposited energy up to ηdep ~10% is obtained using both inductive and capacitor generators. It was shown that maximal efficiency of the HF-laser is reached under high E/p parameter value across the laser gap during excitation pulse (where E is the electric field strength, p is the gas mixture pressure). Application of profilated electrodes along with UV preionization allows to obtain specific output of the non-chain HF-laser of about 140 J/l×atm and total laser efficiency η0~4.5%. It was found that output spectra of the laser in the high efficiency operation mode significantly widen and cascade laser action on some rotational lines of HF molecule vibrational transitions v(3-2) → v(2-1) → v(1-0) is observed.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.