Abstract Photoacoustic imaging (PAI) has been evaluated to visualize small neoplastic lesions inside normal tissues. PAI is based on the detection of pressure waves generated due to the absorption of light energy by a photosensitizer (PS) within the tissue. Porphyrins possess high affinity to tumor tissue thus can be considered as an appropriate PS. PS complexation with metals can increase the heat production at the PS excitation; therefore, increasing the PA response. We have demonstrated the increase of the TPPS4 and TMPyP porphyrin PA response at their complexation with Fe 3 + , Mn 3 + , Cu 2 + and Zn 2 + metal ions in aqueous solutions.