Abstract: Two Sequences of spin-echo Fourier transform (SEFT) experiments with proton decoupling are achieved by FT-80A spectrometer with which ¹³C NMR Spectra can be simplified and C, CH, CH₂ CH₃ carbon resonances can be assigned. Their applications to pure hydrocarbon compounds and aromatic mixtures from petroleum are discribed and compared with simple off-resonance decoupling assignment techniques.