Metal-organic frameworks containing Ga3+ ions and four differently substituted naphthalenedicarboxylates (ndc(2-)) have been synthesized and characterized. The Ga3+ ions are six-fold coordinated by oxygen atoms in all title compounds, but two different inorganic building units, i.e. trans corner-sharing and cis,trans edge-sharing octahedra are observed. Crystal structures were validated by Rietveld refinements against powder X-ray diffraction data. [Ga(OH)(1,4-ndc)]2H(2)O crystallizes in a non-breathing MIL-53 type structure with two different pore sizes (5.5 x 5.5 angstrom and 9 x 9 angstrom). It is non-porous with respect to nitrogen but has a water adsorption capacity of about 155 mg g(-1) and a thermal stability of up to 240 degrees C. The dense compound [Ga(OH)(1,8-ndc)] crystallizes in a new layered structure motif, which is related to the crystal structure of MIL-122 ([Al(OH)((O2C)(4)C6H2)]). The third and fourth compounds [Ga-2(OH)(4)(2,3-ndc)]H2O and [Ga(OH)(2,6-ndc)]H2O are isoreticular to CAU-15 ([Al-2(OH)(4)(2,3-bdc)]H2O) and MIL-69 ([Al(OH)(2,6-ndc)]H2O), respectively. The last two compounds are non-porous toward nitrogen but reversible dehydration was demonstrated. For comparison, the two new compounds [Al(OH)(1,8-ndc)] and [Al-2(OH)(4)(2,3-ndc)]H2O, which are isostructural to the newly described gallium compounds, were also synthesized and fully characterized. The Al-containing coordination polymers exhibit higher temperature stabilities compared to their isostructural Ga compounds.