<P><B>Abstract</B></P> <P>(Red, green and brown) macroalgal biomass is a propitious candidate towards covenant alternative energy resources to be converted into biofuels i.e. hydrogen. The application of macroalgae for hydrogen fermentation (promising route in advancing the biohydrogen generation process) could be accomplished by the transformation of carbohydrates, which is a topic receiving broad attention in recent years. This article overviews the variety of marine algal biomass available in the coastal system, followed by the analyses of their pretreatment methods, inhibitor formation and possible detoxification, which are key-aspects to achieve subsequent H<SUB>2</SUB> fermentation in a proper way.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This review focused on the generation of biohydrogen from macroalgae. </LI> <LI> Key issues affecting H<SUB>2</SUB> production <I>via</I> dark fermentation are presented. </LI> <LI> Discussed various strategies for 5-HMF removal and detoxification. </LI> </UL> </P>