Polyphenoloxidase was extracted from September peach ($_{SE}PPO$) and Summerset peach ($_{SU}PPO$) and its physicochemical characteristics were analyzed. The optimum pH was 6.5 for $_{SE}PPO$ and 5.5 for $_{SU}PPO$. The optimum temperature was $35^{circ}C$ for $_{SE}PPO$ and $39.4^{circ}C$ for $_{SU}PPO$. Activation energy (Ea) from thermal activation was 41.5 kJ/mol for $_{SE}PPO$ and 37.5 kJ/mol for $_{SU}PPO$. Heating at $60^{circ}C$ by 5 min, $_{SU}PPO$ was denatured whereas $_{SE}PPO$ retained 2.6% of activity. Activation enthalpy (${Delta}H^#$) and activation entropy (${Delta}S^#$) for $_{SE}PPO$ heat-inactivation were 69.9 J/mol and $-83.5;kJ/mol{cdot}K$ for $_{SU}PPO$, ${Delta}H^#$ was 91.8 J/mol while ${Delta}S^#$ was $-21.0;kJ/mol{cdot}K$. Substrate specificity ($V_{max}/K_M$) was 4-methylcatechol>catechol>pyrogallol for $_{SE}PPO$ and 4-mehtylcatechol>pyrogallol> catechol for $_{SU}PPO$. For both enzymes, the order of inhibition effectiveness using reductor agents was metabisulphite>ascorbic acid. Benzaldehyde, 4-hydroxybenzaldehyde, and DL-dopa were competitive inhibitors, and their $K_I$ values were 38.86, 8.43, and 2.08 mM, respectively.