Two MOFs, [H2N(CH3)(2)][Zn-3(TATB)(2)(HCOO)]center dot HN(CH3)(2)center dot DMF center dot 6H(2)O (1) and Zn-HKUST-1 (2), were investigated as potential hosts to encapsulate Fe(III) heme (Fe(III) protoporphyrin IX = Fe(III)PPIX). Methyl orange (MO) adsorption was used as an initial model for substrate uptake. MOF 1 showed good adsorption of MO (10.3 +/- 0.8 mg g(-1)) which could undergo in situ protonation upon exposure to aqueous HCl vapor. By contrast, MO uptake by 2 was much lower (2 +/- 1 mg g(-1)), and PXRD indicated that structural instability on exposure to water was the likely cause. Two methods for Fe(III)PPIX-1 preparation were investigated: soaking and encapsulation. Encapsulation was verified by SEM-EDS and showed comparable concentrations of Fe(III)PPIX on exposed interior surfaces and on the original surface of fractured crystals. SEM-EDS results were consistent with ICP-OES data on bulk material (1.2 +/- 0.1 mass % Fe). PXRD data showed that the framework in 1 was unchanged after encapsulation of Fe(III)PPIX. MO adsorption (5.8 +/- 1.2 mg g(-1)) by Fe(III)PPIX-1 confirmed there is space for substrate diffusion into the framework, while the UVvis spectrum of solubilized crystals confirmed that Fe(III)PPIX retained its integrity. A solid-state UVvis spectrum of Fe(III)PPIX-1 indicated that Fe(III)PPIX was not in a mu-oxo dimeric form. Although single-crystal XRD data did not allow for full refinement of the encapsulated Fe(III)PPIX molecule owing to disorder of the metalloporphyrin, the Fe atom and pyrrole N atoms were located, enabling rigid-body modeling of the porphine core. Reaction of 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) with H2O2, catalyzed by Fe(III)PPIX-1 and -2, showed that Fe(III)PPIX-1 is significantly more efficient than Fe(III)PPIX-2 and is superior to solid Fe(III)PPIX-Cl. Fe(III)PPIX-1 was used to catalyze the oxidation of hydroquinone, thymol, benzyl alcohol, and phenyl ethanol by tert-butyl-hydroperoxide with t(1/2) values that increase with increasing substrate molecular volume.