As a steady renewable energy technology, biogas is a viable alternative to reduce our dependency to fossil fuels and to prevent severe climate change. Biogas potential can be improved through combining different types of substrate and inoculum, as well as through substrate pre-treatments. This study aims to observe and explore the potential of macroalgae Saccharina latissima as a promising new source in renewable energy technology. The biomethane potential of macroalgae in mixture with additional substrate of mixed waste paper will be studied as a mean to improve the biogas yield. It will also compare the biomethane results of the macroalgae and the mixed substrate (macroalgae plus waste paper) exposure to non-thermal and thermal pre-treatment. In the experiment, the ratio of 3 : 1 for gr VS inoculum : gr VS substrate is used in a quantitative BMP test up to 25 days of incubation. The substrate was pre-treated mechanically (blended) into slurry and thermally through pre-heating at high temperature (130°C, 45 minutes) before digested by the inoculum. In the end of incubation period at STP (0°C and 1 atm), the highest cumulative methane yield of 260.91 Nml CH4/gr VS substrate was achieved by sample in Var – I, while the control has cumulative methane yield of 50.52 Nml CH4/gr VS. Thermally pre-treated samples resulted in lower BMP yields than the ones which were not thermally pre-treated. Through the ANOVA t-test of the methane volume and biomethane potential (BMP) yields, it is concluded that the thermal pre-treatment and waste paper addition only give little effect to biomethane production from macroalgae.