In this thesis the quantitative analysis of two peptide drugs, consisting of octreotide and oxytocin carried out, using electrospray ion mobility spectrometry for first time. Ion mobility spectra were obtained for both drugs. In the spectrum related to each drug, two peaks appeared. Reduced mobility values of 1.171 and 0.651 (cm 2 V -1 s -1 ) for octreotide and 1.23 1 and 0.655 (cm 2 V -1 s -1 ) for oxytocin were obtained. For quantitative analysis, the presence of acetic acid and water on signal intensity of these two substances was studied and percent of water-acid optimized value was obtained. At first, the quantitative analysis of octreotid in the mixture was done, that was as so: 1: 29: 70 (acid: water: methanol). In each analysis, ion mobility spectrum was recorded and integral of area below the peaks, when signal intensity was maximum, was registered as instrument response. In this case, linear range was 0.05-1 micro molar and detection limit was 0.007 micro molar. Relative standard deviation was 2.7%. Oxytocin too, was analysis similarly. Linear range and detection limit 0.3-10 and 0.04 micro molar were obtained, respectively. Relative standard deviation was 2.7%. In this thesis, the liquid- liquid electro extraction method was used for the sample preparation, which is independent of the peptide?s isoelectric point, hydrophilicity or hydrophilicity. In order to a cell (Glass tube with a diameter of 15 mm and length 108 mm and a conical end) designed and made. A rod electrode made of platinum with a diameter of 0.5 mm as the cathode was welded to the end of cell. A electrode with a flat circled end made of gold with a diameter of 15 mm as anode were used. The time of 15 minute and the potential of 5kV were chosen as optimum time and potential for extraction. For both substances, calibration curve was obtained. Linear ranges were 0.1-2 and 0.7-10 micro molar for octreotide and oxytocin, respectively. Detection limits were 0.02 and 0.08 micro molar for octreotide and oxytocin, respectively. Relative standard deviations of 2.5% for octreotide and 2.9% for oxytocin were obtained. Also, the recovery percentage was for octreotide 40-44 and 40-46 for oxytocin. Considering these represented results, it is expected that this peptide analysis method whit advantage such as simplicity, fast response, suitable detection limit and linear dynamic rang be used for quantitative analysis of peptides in biologicale and pharmacology fields.