Single crystal of oxalato-bridged, Cesium-extended frame work, Cesium Hydrogen Oxalate Dihydrate (CHOD), has been synthesized by slow evaporation solution growth technique. Diffraction studies were used to identify the geometry of the atoms present in the primitive cell of the crystal. The title compound has crystallized in triclinic category-bearing space group P-1. Spectroscopic investigation of the compound was done by FTIR and FT-Raman techniques. From UV–Vis studies, optical absorption edge was ascertained as 241 nm. It has excellent optical transmission window throughout the visible region. Energy dispersive X-ray analysis (EDAX) affirms the presence of Cesium in the compound. Fluorescence decay of the molecules present in the excited state for the crystal was studied. Hirshfield surface maps intermolecular contacts present in the crystal and the contributions made by the contacts were assessed by 2D Finger print plots. Z-Scan studies ascertain the magnitude of nonlinear refractive index and nonlinear refraction. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.