In this study, twenty one benzoquinones, eleven halobenzoquinones, four bromo-hydroquinoes and six alkyl-bromobenzoquinones were synthesized and well-characterized by means of spectroscopic methods. Five of those mentioned above were identified to be new compounds. All synthesized compounds together with three commercially available hydroquinones were subjected to brine shrimp Artemia salina Leach. lethality test. It was observed that there was indeed relationship between the structure and biological activity. Halobenzoquinone derivatives containing one bromine atom and a methyl group at C-2 exhibited a high lethality activity. In the case of alkyl-halobenzoquinones, the high activity was observed when the halobenzoquinones had long side chain at C-2, while bromohydroquinone derivatives also displayed high activity when there were three bromine atoms and a methyl group attached to the parent compound. In contrast to benzoquinones, the high reactivity was detected when the substituent was a hydrogen atom or a short carbon chain. Hydroquinones with a methyl group at C-2 position also revealed high activity.