Zirconia-supported tungsten oxide (WO₃/ZrO₂ or WZ) is known as an efficient catalyst for selective acrolein (AC) production from gas-phase dehydration of glycerol (GL). Two catalysts (WZ-CP and WZ-AN) were prepared herein using, respectively, a ZrO(OH)₂ hydrogel (ZrO(OH)₂-CP) and its derived alcogel (ZrO(OH)₂-AN) for a precursor of ZrO₂. To optimize the reaction variables and improve the catalyst performance, the WZ-CP catalyst was employed to show the effects of (A) reaction variables (temperature, partial pressures of GL and H₂O, and co-feeding H₂ or O₂); (B) catalyst modification with alkali and alkali earth metal ions (Na⁺, K⁺ and Mg²⁺), or transition metals (Pt, Pd, Rh and Ni). The reaction at 315 °C always produced the highest AC selectivity, and this temperature was then used to investigate the effects of the other variables and catalyst modifications. Increasing the molar GL/H₂O ratio led to lower AC selectivity and accelerated the catalyst deactivation. Introducing 4–8 kPa O₂ to the reaction feed significantly reduced the catalyst deactivation rate but the AC selectivity was only slightly lowered. However, an addition of 4 kPa H₂ produced almost no effect on the reaction. The modified catalysts performed no better during the reaction unless the modifier was Pt or Pd, whose catalytic stabilities in the O₂-containing (4 kPa) feed were significantly higher and their selectivity for AC production slightly lowered. Working under the conditions optimized with WZ-CP, the WZ-AN catalyst offered a high AC yield (62–68%) for longer than 30 h, during which the GL conversion remained higher than 93%.