Co-liquefaction of micro algae (Chlorella, Spirulina, and Littorale) with coal (Australian Yallourn brown coal and Illinois No. 6 coal) was carried out under pressurized Hz in l-methylnaphthalene at 350-400 degreesC for 60 min with various catalysts. Co-liquefaction of Chlorella with Yallourn coal was successfully achieved with excess sulfur to iron (S/Fe = 4), where sufficient amount of Fe1-xS, which is believed to be the active species in the coal liquefaction, was produced. The conversion and the yield of the hexane-soluble fraction were close to the values calculated from the additivity of the product yields of the respective home-reactions. In the reaction with a one-to-one mixture of Chlorella and Yallourn coal, 99.8% of conversion and 65.5% of hexane-soluble fraction were obtained at 400 degreesC with Fe(CO)(5) at S/Fe = 4. When Littorale and Spirulina were used as micro algae, a similar tendency was observed with the iron catalyst. On the other hand, in the coliquefaction with Illinois No. 6 coal, which is known to contain a large amount of sulfur in the form of catalytically active pyrite, the oil yield in the co-liquefaction was close to the additivity of the respective reaction with Fe(CO)(5)-S, even at S/Fe = 2. Ru-3(CO)(12) was also effective for the. co-liquefaction of micro algae with coal.