Novel uranyl acrylate complexes with general formula R[UO 2 (CH 2 CHCOO) 3 ] (R?K + , NH 4 + , Rb + , or Cs + ) were synthesized and characterized by X-ray diffraction, IR spectroscopy and second harmonic generation (SHG) measurements. All four compounds are isostructural and crystallize in the non-centrosymmetric P2 1 3 space group. Acrylate anions act as bidentate chelating ligands forming [UO 2 (CH 2 CHCOO) 3 ] - complexes which are connected through electrostatic interactions with counter ions. SHG measurements revealed the inverted correlation between the Q=I 2 ω /I 2 ω SiO 2 values and the radii of counter ions.