Studies on the preparation of leach-resistant insoluble boron compound from simulated solution of evaporator concentrate are reported in this work. The insoluble compound CaB 6 O 1 0 4H 2 O has been prepared from simulated solution of evaporator concentrate by chemical treatment with calcium chloride solution. Other insoluble compounds CaB 2 O 4 6H 2 O/Ca 3 B 4 O 9 9H 2 O/Ca[B(OH) 4 ] 2 2H 2 O and NaCaB 5 O 6 8H 2 O/NaCaB 5 O 6 (OH) 6 5H 2 O/ Ca 2 B 6 O 1 1 13H 2 O have been prepared from simulated solution of evaporator concentrate with calcium hydroxide under controlled conditions of temperature and time. Identification and characterization of these compounds have been done by X-ray diffraction, optical microscopy and differential thermal and thermogravimetric analysis. For low-level radioactive waste treatment, immobilization of insoluble borate compounds in bitumen will produce leach-resistant suitable waste product for safe disposal.