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We have completed a series of high-resolution radio recombination line (RRL) observations toward G10.62. This ultracompact (UC) H II region, one of the brightest IRAS point sources, is thought to be ionized by an O4 - 05.5 star embedded in molecular cloud. Keto, Ho and Haschick (1988) have proposed a collapsing core model for the surrounding molecular gas based on high spatial resolution observations in NH$_{3}$. Our subarcsecond-resolution RRL observations probe the dynamics of the central ionized medium. We observe velocity structure in the ionized gas similar to that observed in NH$_{3}$, and the H65$\alpha$ line is dynamically broadened throughout the nebula. The core density is greater than 10$^{5}$ cm$^{-3}$, and its temperature is approximately 8000K, compared to 6000K in the nearby diffuse cometary H II region, perhaps implying quenching of coolants in very dense H II regions. We also observe impact broadening in the H110$\alpha$ line toward the core.
