The titled compound Al₂(WO₄)₃was synthesized by a conventional solid state reaction and characterized by powder XRD. It crystallizes in an orthorhombic (Pbcn, No. 60) lattice, with unit cell parameters as 12.582(2), 9.051(1), 9.128(2)̊A, and V=1039.5(3) (̊A)³. The compound was found to show negative thermal expansion (NTE) behavior in the temperature range of 25 to 850⁰C. The average linear NTE coefficient (α1), in this temperature range, ^₋₁.5×10⁻⁶ K⁻¹. The effect of pressure at ambient temperature, was studied by a Bridgman Anvil (BA)  apparatus, to reveal that there is no irreversible phase transition up to 8 GPa.The effect of high pressure and high temperature on this compound was studied by a Toroid Anvil (TA) apparatus. This compound has a limited stability under high pressure and temperature, as it undergoes a decomposition to AlWO₄ and WO_3−x with a partial oxygen loss. As an off-shoot of this work, certain new modifications of WO _3−x under pressure and temperature were observed, viz., monoclinic, tetragonal and an orthorhombic modifications at 5 GPa/1400⁰C, 3 GPa/900⁰C and 1.8 GPa/1030⁰C, respectively. The detailed XRD studies of the products are presented here.