In this work, several acid-activated catalysts were tested in the isomerization reaction of α-pinene to obtain camphene, a very high-value-added chemical. Titanium-based precursors (H₂TiO₃ powder, TiO₂ powder, and TiO₂ nanopowder) were activated using a variety of acids to prepare acid-activated catalysts, and the catalysts were characterized by XRD, SEM, IR, Py-IR, and BET methods to determine the structure–activity relationship between the catalyst acidity, pore structure and catalyst isomerization performance. The results showed that the catalyst surface area and total acidity increased with the acid activation of precursors. The conditions that affect the reactions were studied, including the type of acid treatment and titanium-based precursor used for activation, reaction temperature, and weight hourly space velocity. Preliminary studies showed that the most active catalyst was the TiO₂ nanopowder activated by hydrochloric acid. Under optimized conditions, α-pinene was completely converted with high selectivity (63.96%) towards camphene, which has a higher commercial value. The variation law of product distribution with time was also studied in order to investigate the isomerization mechanism of α-pinene. A catalyst regeneration experiment demonstrates the exceptional stability and regenerative capabilities of the catalyst.