The synthesis and characterisation of AM-18 (Aveiro-Manchester structure number 18), a large-pore framework sodium titanium silicate catalyst, is reported. The as-synthesised material was characterised by powder X-ray diffraction (XRD), thermogravimetry (TGA) and differential thermal analysis (DTA), scanning electron microscopy (SEM) and chemical analysis by energy dispersive analysis of X-rays (EDAX), nitrogen and benzene adsorption measurements, ²³Na triple-quantum (MQ) magic angle-spinning (MAS) and ²⁹Si MAS NMR, Fourier transform infrared (FTIR) and Raman spectroscopies. The latter two techniques indicate that this novel titanium silicate may contain five-coordinated titanium. AM-18 shows high thermostability (in excess of 650 °C). Isopropanol conversion was used as a model reaction to study the acid–base properties of as-synthesised AM-18. This material exhibits high catalytic activity (71% conversion) and selectivity for propene (74%).