The deactivation of the S1(π,π*) excited state of nickel tetraphenylporphine has been investigated using various transient grating techniques. By measuring the density changes of the sample occurring during this process, the excited state, that is responsible for the ground state recovery time of 250 ps, was determined to lie 1.18±0.13 eV above the ground state. This value suggests that this state is the 1(d,d) state.