The disclosure provides a thermoelectric composite sandwich structure with an integrated honeycomb core and method for making. The thermoelectric composite sandwich structure comprises two prepreg composite face sheets and an integrated honeycomb core assembled between the face sheets. The honeycomb core comprises a plurality of core elements bonded together with a core adhesive. Each core element has a first side substantially coated with a negative Seebeck coefficient conductive material having a plurality of first spaced gaps, and each core element further has a second side substantially coated with a positive Seebeck coefficient conductive material having a plurality of second spaced gaps. The honeycomb core further comprises a plurality of electrical connections for connecting in series the first side to the second side. A temperature gradient across the honeycomb core generates power.