I studied and carried out my experiments in the Department of Applied Chemistry at the University of Debrecen, Hungary. Using a soft ionization technique (Electrospray Ionization), I was able to study the fragmentation and fragmentation pathways of 1,3,5-trisubstituted 2-pyrazoline derivatives in both positive and negative ion modes. In the normal MS mode, we cannot select and study an ion along with its fragments for structural elucidation; we can only gain basic information about the masses of the ions of the sample to be studied. The MS/MS mode on the other hand, makes it possible to gain more knowledge about the structure of the sample being investigated by enabling the fragmentation as well as the separation of the ions. The MS/MS method was done using a microtof-Q instrument which employed a Quadrupole analyser for the mass selection of the precursor ions and a Time of Flight analyser for the separation of the ions. Furthermore, I derived a survival yield plot, showing a particular sample (sample 10) which I studied in both its positive and negative ion modes. The survival yield shows the fragmentation stability of the molecules. Based on the result from the survival yield plot of sample 10, it can be seen that for the deprotonated form of the sample, higher collision energy is needed for the fragmentation of the molecules. Lesser energy is required for fragmentation of the sample in its protonated form. I also observed that the main types of fragmentation for the 2-pyrazolines are the fragmentation of the substituents and also the fragmentation of the pyrazoline ring.