The dehydration of poly(vinyl alcohol) by concentrated sulfuric acid ^[1] at room temperature generates a stable gel made of polyacetylene swollen by sulfuric acid. Like other types of sulfuric acid gels ^[2], this polymeric material can have important technological applications (e.g., surface etching agent for off-set or intaglio printing, pickling for metals, acid reservoir for gradual/controlled water acidification, reactant in chemical syntheses like sulfonation, electrolyte for storage battery, etc.).