To provide an apparatus for on-line continuous production of various grades of Ca grease products starting from introduction of the feedstock to the products.

The apparatus for the on-line production of Ca grease comprises a reaction vessel 1 where a Ca source and a fatty acid are reacted in the presence of a base oil to form a Ca soap; a first pipeline 2 which leads the reaction product withdrawn from the bottom of the reaction vessel to a cooling step 5; a second pipeline 3 which leads the grease after the cooling step to an adjustment step 6; a third pipeline 4 which leads the grease after the adjustment step to a product vessel 7; a pipeline 8 for introducing a cooling oil connected to the upstream side of the cooling step; and a pipeline 9 for introducing an adjusting oil connected upstream of the adjustment step. The cooling step 5 and the adjustment step 6 are constituted by line mixers L1 and L2, respectively, or static mixers S1 and S2 and line mixers L1 and L2 arranged in series in this order, respectively.