  We present a study of the compact H II region N66A in the SMC pre-eminent
starburst region N66/NGC346. Despite extensive research on various components
of the N66/NGC346 complex, few studies have so far focused on N66A, which is a
special object in the whole complex and therefore deserves scrutiny. The study
of this compact H II region and its fellow objects seems important in the
framework of massive star formation in the Magellanic Clouds. This analysis is
based mainly on our optical ESO NTT observations, both imaging and
spectroscopy, coupled with archive HST ACS data and Spitzer infrared images
(IRAC 3.6, 4.5, 5.8, and 8.0 microns). We derive a number of physical
characteristics of the compact H II region N66A. Moreover, we present the
spectral classification of the main exciting star of N66A for the first time
using spectroscopy. Its spectral features indicate a main sequence massive star
of type O8. We compare this result with that based on the stellar Lyman
continuum flux estimated from the ionized gas H-beta flux. The compact H II
region belongs to a rare class of H II regions in the Magellanic Clouds, called
High-excitation Blobs (HEBs). N66A most probably represents a very young
massive star formation event in the N66 complex, which has a range of ages.
