A new compound with formula SrCH3PO3·3H2O has been prepared, characterized by thermogravimetry, IR spectroscopy and powder X-ray diffraction, and its structure has been determined from single-crystal X-ray diffraction data. Strontium methylphosphonate trihydrate crystallizes in an orthorhombic system with space group Pbca (No. 61), Z = 8 and with lattice parameters a = 7.8838(6), b = 8.5173(5), c = 21.5272(15) Å. Primary alcohols, amines, and 1,2-diols with straight carbon chains were intercalated into this strontium methylphosphonate compound. For all three types of intercalate, a linear dependence of the interlayer distance on the number of carbon atoms in the aliphatic chain of the guest was found. From these results, the arrangements of the guest molecules in the interlayer space of the host (SrCH3PO3) structure were deduced. The amine intercalates are unstable, and the guest species can be released from the host by washing the intercalate with an aprotic solvent. Conversely, the alcohol and diol intercalates are surprisingly stable. The reason for this stability may be due to the fact that the oxygen atom of an alcohol or diol species can replace the oxygen atom of the coordinated water molecule in the host. A successful attempt to intercalate polymeric species, namely poly(ethylene glycol), was made, which opens the way for the preparation of nanocomposites with this type of hostmaterial.