β Acknowledgement is made to the National Science Foundation for support of this research.Author Institution: Noyes Chemical Laboratory, University of IllinoisHalf-widths at half-height of 10-12 kc have been achieved in a high-resolution study of the spin-rotation multiplets in the microwave spectrum of OF2β. Several transitions in the J = 9-14 region have been completely resolved yielding the diagonal elements of the spin-rotation interaction tensor. The values in kc along the principal inertial axes are Maaβ=β385,Mbbβ=β120, and Mccβ=β83. These values give the best fit of the experimental data assuming a rigid molecule. A complete analysis of the data acknowledging the vibration-rotation interactions is in progress. Various aspects of the spin-rotation interaction and its relation to the chemical shift and bonding properties of the molecule will be discussed