We present an analysis of Spitzer-IRS spectroscopic maps of the L1157 protostellar outflow in the H2 pure-rotational lines from S(0) to S(7). The aim of this work is to derive the physical conditions pertaining to the warm molecular gas and study their variations within the flow. The mid-IR H2 emission follows the morphology of the precessing flow, with peaks correlated with individual CO clumps and H2 2.12 ?m ro-vibrational emission. More diffuse emission delineating the CO cavities is detected only in the low-laying transitions, with J lower2 line images have been used to construct two-dimensional maps of N(H2), H2 ortho-to-para ratio (OPR), and temperature spectral index ?, in the assumption of a gas temperature stratification where the H2 column density varies
