Experimental calcium sulphate bone cement has been tested by ultrasounds to characterise its progressive setting through the evolution of several acoustic properties. The acoustic impedance z(t), the density rho (t) and the speed of sound c(t) versus the curing time have been monitored during the viscous-to-solid transition of the cement as a function of different mixing conditions. Injectability tests were also performed and the results have been related to the acoustic properties measured previously. It has been observed that further mixing after cement's constituency, and before the initial setting time of the cement, drastically affects both the characteristic setting times and the injectability of the cement.