Single crystals of two new cobaltites, Ba2Co9O14 and Ba3Co10O17, were obtained from the flux of K2CO3 in the temperature range 800-890 degrees C. They crystallize in an intergrowth structure containing perovskite block and Cdl(2)-type layers and can be attributed to the n = 1 and 2 members in a new intergrowth series of cobaltites, Ban+1ConO3n+3(Co8O8). Both Ba2Co9O14 and Ba3Co10O17 are metastable and transform into the known 2H-perovskite-related oxides at high temperature.