The ¹H NMR chemical shifts of the C(α)H protons of arylmethyl triphenylphosphonium ions in CD₂Cl₂ solution strongly depend on the counteranions X⁻. The values for the benzhydryl derivatives Ph₂CHPPh₃⁺ X⁻, for example, range from δ_H=8.25 (X⁻=Cl⁻) over 6.23 (X⁻=BF₄⁻) to 5.72 ppm (X⁻=BPh₄⁻). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl⁻ > Br⁻ ≫ BF₄⁻ > SbF₆⁻. For the less bulky derivatives PhCH₂PPh₃⁺ X⁻, we also find CH⋅⋅⋅Ph interactions between C(α)H and a phenyl group of the BPh₄⁻ anion, which result in upfield NMR chemical shifts of the C(α)H protons. These interactions could also be observed in crystals of (p-CF₃-C₆H₄)CH₂PPh₃⁺ BPh₄⁻. However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the CH⋅⋅⋅X⁻ hydrogen bonds between the phosphonium ion and anions, in particular Cl⁻ or Br⁻. This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh₄⁻ anions. The concentration dependence of the ¹H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD₂Cl₂ solution. The cation–anion interactions increase with the acidity of the C(α)H protons and the basicity of the anion. The existence of CH⋅⋅⋅X⁻ hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl⁻ and Br⁻ salts in CD₂Cl₂ solution show strong red-shifts of the CH stretch bands. The CH stretch bands of the tetrafluoroborate salt PhCH₂PPh₃⁺ BF₄⁻ in CD₂Cl₂, however, show a blue-shift compared to the corresponding BPh₄⁻ salt.