Abstract: Calcium phosphat cement in β-calcium phosphate (β-TCP) dicalcium phosphate dihydrate (DCPD) -water (H₂O) system with addition of citric acid and malonic acid was studied．Compressive strength of the resulted samples was 36.23 MPa after ageing in nearly physiological conditions (100％ relative humidity, 37±1℃). The hardening time of the cement system was about 5～20min. The citric acid and malonic acid could effeetively control the hardening time. According to X-ray diffraction patterns IR spectra and scanning electron micoscopic observation, hydroxyapatite(HAP) played an important role in cementing and hardening. An increase in the strength of the cement was attributed to the calcium citrate present in the cement．

Key words: biocement, organic acid