AbstractThis Review describes and assesses known solid‐state examples of halide hydrates that are discrete in nature. Most of these are chloride hydrates, and most discrete clusters are dihalides, with very few mono‐ or multi‐halide species found in the solid state. Polymeric chloride hydrates, on the other hand, are mostly 2D layered structures. We also observe that there is a gap in the chloride:water ratio between 8–20 waters per chloride. Isolated clusters can be found with 1–3 waters per chloride, 2D layers with 2–8 waters, and 3D semiclathrates with 20–38 waters. However, 1D chains comprise only 1–2 waters per chloride. [Cl(H₂O)]⁻ is the only species found in both the solid state and gas phase and is also the only halide hydrate with a free OH group. Infrared spectra in the ν(OH) region are distinctive and useful for identification. Agreement between computed (gas phase) and experimentally‐observed solid state structures and their vibrational spectra gives us confidence that discrete halide hydrate species observed in the solid state provide a useful link between gas phase species and structural motifs of halide hydrates in solution, especially microsolvated ion‐pairs.