Abstract: This paper contains two parts: (1) Trisubstituted Cyclopropane and FluorinatedAlkynone; (2) Phosphate Ester and Phosphonyl Compounds. The positive and negativeion chemical ionization (PNCI) mass spectra of eleven trisubstituted cyclopropanes andfour fluorinated alkynones have been reported with reagent gases methane and isobutane.The EI positive and PNCI mass spectra of p-substituted benzyl cyanide phosphate esterand phosphonyl compounds have been analysed with reagent gas methane.