Bioethanol production was investigated in red algae Portieria hornemannii which belongs to the family Rhizophyllidaceae. Saccharomyces cerevisiae was cultured on Potato Dextrose Agar (PDA) media that had been sterilized at a temperature of 121°C and at a pressure of 1 atm for 15 min. It was incubated at 30°C for 3 days. Microbes on PDA media as culture stock was regenerated on the Yeast Extract Peptone Dextrose (YPD) media at 30°C for 24 h before mixing with hydrolysate. Reducing sugar was determined by 3,5-dinitrosalicylic acid (DNS) method. The seaweed hydrolysate from 60 g of seaweed gel (15 g of seaweed) yielded alcohol maximum in fermentate using S. cerevisiae as fermentation agent. Fermentation to produce alcohol was carried around 36-168 h. Bread yeast S. cerevisiae was found suitable for the bioethanol fermentation of seaweed hydrolysate, and gave an alcohol content of fermentate after 20-40 h of fermentation at room temperature.