The electronegativities of -SF���, -CF���SO���, and -SO���F have been measured with gas phase X-ray photoelectron spectroscopy. Of these three groups previously measured values were found only for -SF���. The electronegativities of -Cl, -Br, -CF���, and -CF���, were concurrently measured to determine how the findings of this research compare with other experimental values found in the literature. Our experimental electronegativities for -SF���, -CF���SO���, and -SO���F are 2.81 �� 0.12, 2.49 �� 0.09, and 2.92 �� 0.12 respectively. The electronegativity of -CF���, currently measured (2.78 �� 0.08) is significantly lower than other experimental values. The electronegativity of -SF��� is in agreement with other experimental values. The experimental electronegativities are compared with theoretical values calculated based on the assumption of Electronegativity Equalization and based on Mulliken's definition of electronegativity. It is found that the electronegativities calculated with Electronegativity Equalization are higher than the experimental values currently measured, and those calculated with Mulliken's definition are lower than the experimental values. / Graduation date: 1999