The document discusses I-functions and H-functions, which generalize Fox's H-function and contain certain Feynman integrals and partition functions as special cases. It establishes new double integral relations for products involving I-functions and H-functions. Specifically, it derives double integral relations for (A) a product of an I-function and H-function, and (B) the composition of an H-function with another H-function, under certain conditions on the parameters. These relations unify and extend previous known results for various special functions.