Oxidation of p-chlorobenzaldehyde and p-methyl benzaldehyde by Isoquinolinium bromochromate has been examined in acetic acid medium. The proposed intermediate involves in complex formation between H₂CrO₄ species of oxidant and keto form of substrate. The rate of reaction is enhanced by an increase in [H+], catalyst Cu++ ion, and increase in percentage of acetic acid (v/v). The effect of relative permittivity neutral salt, ionic strength and temperature was also carried out in support of the mechanism proposed. The derived rate law was verified graphically. We observed the oxidation with stoichiometric amounts (1:1) oxidant and substrate in the range of temperature 35°C and 40°C.