Abstract- In pyrolysis, tar is undesired byproduct because it causes operational problems such as the contamination in the inner wall of a reactor, blockages in pipes, corrosion and formation of tar aerosols and carcinogenic. Therefore, it is necessary to take steps for removing or decomposing tar into fuel gas (bio-syngas) and other compounds that are more useful. In this experiment, catalytic process was selected to decompose tar derived from wood waste pyrolysis. The study was focused on the effect of temperature on catalytic tar decomposition using a fixed bed reactor with using Indonesian iron ore as catalyst. Initially, tar was vaporized inside preheater at temperature of 450°C, and then was passed through the catalyst bed. The variables studied were temperatures between 500 – 700°C and height of catalyst bed between 0.67 – 1.34 cm. Yields of gas, bio-oil, char and aqueous and also compositions of gas and liquid product were evaluated. The liquid product are represented in terms of acid compounds, hydrocarbon compounds, ketone compounds, oxygenate compounds, aromatic hydrocarbon - one cyclic (AH-1), poly aromatic hydrocarbon - two cyclic (PAH-2) and poly aromatic hydrocarbon - three cyclic (PAH-3). The results showed that the yields of gas and char increased by increasing temperature from 500 to 700°C, while bio-oil decreased. In addition, increasing temperature resulted new compounds of AH-1, PAH-2 and PAH-3. The yields of PAH-2 and PAH-3 on liquid product and hydrogen and methane on gas product also increased, while yields of acid, ketone, AH-1 decreased. Keywords Tar, biomass, catalytic decomposition, low grade iron ore.