Standardized experimental and calculated X-ray powder diffraction data for a new synthetic zeolite, cesium titanium silicate, CsTiSi2O6.5, are reported. In addition, a structure model in space group Ia3d (230), which is isomorphous with the mineral pollucite (CsAlSi2O6·xH2O), is proposed for CsTiSi2O6.5. This structure model is the basis of the reported calculated X-ray powder diffraction data for CsTiSi2O6.5. The experimental pattern for CsTiSi2O6.5 shows this compound crystallizes in a body-centered cubic (BCC) unit cell with a=13.8423 (1) Å. The measured value of the reference intensity ratio (I/Ic) of CsTiSi2O6.5 is 2.37, while the contrasting calculated value of I/Ic is 4.45. The experimental density (Dm) of CsTiSi2O6.5 is 3.48±0.09 g/cm3, in agreement with the calculated density (Dx) of 3.42 g/cm3. Chemical analysis of CsTiSi2O6.5 by atomic absorption spectroscopy gives its composition as 54±2 wt% Cs; 23±2 wt% Ti; 23±2 wt% Si, which compares favorably with the theoretical composition of 56 wt% Cs; 20 wt% Ti; 24 wt% Si.