The structure of anhydrous cyanuric acid, its intermolecular interactions and thermal parameters have been described in 1971 by G.C. Verschoor . In the following years, i.a., strong donor-acceptor interactions connected with occurrence of N–H and C=O functional groups were investigated by T.C. Lewis  for the anhydrous form as well for readily formed solvates and co-crystals. Possibility of satisfying all the hydrogen bonding functionalities and it’s influence on the crystal structure were verified.
I am presenting experimental charge density analysis for the cyanuric acid dihydrate. Electron density distribution was described with Hansen and Coppens pseudoatom model. Crystal structure, occurring interactions and vibrational parameters were compared with periodic theoretical calculations both for dihydrate and anhydrous form. Molecular interactions with water molecules were also justified basing on the TGA/DSC measurements.