The study investigates prominence patterns in Czech-accented English comparing the production of non-native speakers of English at two distinct stages of phonological acquisition (beginners and intermediates) with a native performance. Word stress in Czech is entirely different from English, it has a fixed position, a delimitative function and rather impalpable acoustic manifestations. Alternations in the realization of word stress were analyzed by measuring the ratios or differences of acoustic correlates of prominence: duration, fundamental frequency, sound pressure level and spectral slope. Since word stress is a relational phenomenon, these characteristics were measured in two adjacent syllables one of which was a canonical stress bearer. The results reveal a clear difference between native and non-native treatment of word stress in all parameters examined. In the non-native sample distinct interferences of L1 across the two groups were detected: the subjects displayed different exploitation of duration, spectral slope and sound pressure level (SPL) with relation to their proficiency in L2 English. Out of these, duration ratio proves to be the most significant correlate. Furthermore, our findings indicate a strong effect of prosodic context coinciding with the prominence features, particularly in intonation declination and phrase-final lengthening.