In this work, activities of modified dolomite catalysts using calcium acetate in the heterogeneously catalyzed transesterification of microalgae oil with methanol were investigated. Modified catalysts were prepared via wet impregnation method and calcined 850 degrees C for 2 h. Reaction conditions were examined as the catalyst type, amount of catalyst, methanol/microalgae oil molar ratio, and reusability of the catalyst using the dolomite and modified dolomite catalysts. When investigated reusability of the modified dolomite catalyst in the transesterification of microalgae oil with methanol, catalyst was reused three times with a small loss of activity. After fourth run, reused catalyst was calcined again and got similar activity to the first run. The highest fatty acid methyl esters (FAME) yield of 90% was obtained when the reaction was performed with methanol/microalgae oil molar ratio of 6:1, catalyst amount of 3%, and reaction temperature at 65 degrees C for 3 h by using the 30% CaO/dolomite catalyst.