Preliminary pyrolysis studies of macroalgae biomass (Ulva cf. flexuosa and Hy. edulis) which were collected from several coastlines of Peninsular Malaysia were performed by using thermogravimetric analysis (TGA). The corresponding kinetic parameters were calculated through three model-free methods, namely Kissinger, Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO). The TGA curves of both species exhibited three degradation stages: dehydration, devolatilization, and residual decomposition. The devolatilization stage is where the main pyrolysis occurred at a temperature around 150-590oC and released the total volatiles of 56.93% and 54.92% for Ulva cf. flexuosa and Hy. Edulis. The calculation of activation energy from Kissinger method for Ulva cf. flexuosa was 180.24 kJ/mol while 194.86 kJ/mol for Hy. edulis. The apparent activation energies for KAS and FWO methods are increased by increasing the pyrolysis conversion with average activation energies of 241.17 kJ/mol and 253.65kJ/mol for Ulva cf. flexuosa, while for Hy. edulis, are 244.75 kJ/mol and 258.9 kJ/mol. This study provides the basis for the further application for designing and modeling in thermochemical conversion system of macro algae biomass.