Abstract Chalcone is an important biosynthetic precursor, due to the diverse pharmacological activities. The aim of this current study was to synthesize 14 new chalcone derivatives compounds by incorporating p-alkoxyacetophenones with substituted benzaldehydes. Two new series of chalcone derivatives have been synthesized using the alkylation and the base catalysed Claisen-Schmidt condensation. All the synthesized compounds were fully characterized by IR, 1D NMR (1H and 13C NMR) and 2D NMR (COSY, HMQC, HMBC) as well as mass spectrometry analysis. All the synthesized compounds were assayed in vitro for their antituberculosis activities against Mycobacterium tuberculosis strain. Among them, compounds (E)-1-[4-(heptoxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5a), (E)-1-[4-(octyloxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5b) and (E)-1-[4-(decyloxy)phenyl]-3-(2-hydroxy-5-bromophenyl)prop-2-en-1-one (5d) showed good activities with the lowest MIC value of 12.5 μg/mL.