Deuterium fluoride vibrational energy transfer measurements have been performed at 198, 209, 232, 264, and 296°K using the laser excited vibrational fluorescence technique. Rate contants for the following processes have been determined: HF(v=1)+DF(v=0) →ke+k12 HF(v=0)+DF(v=1,0) ÷ΔE=1055,3962 cm−1, DF(v=1)+DF(v=0) →k222DF(v=0)+ΔE=2907 cm−1, DF(v=1)+Ar→k2mDF(v=0)+Ar+ΔE=2907 cm−1. Experimental results taken at 198, 209, and 232°K exhibited rate enhancements for increasing DF pressure which is most easily explained as HF(v=1) and DF(v=1) quenching by (DF)n. Relaxation rates in this regime were best described by the empirical equation τ−1=C exp(DPDF), where C and D are temperature dependent coefficients and PDF is the total DF pressure, [DF+(DF)n]. The variation τ−1 with exp(PDF) cannot be reconciled in terms of a monomer–dimer model only. Higher order terms (n=4 and 6) are expected to dominate the collisional quenching of HF(v=1) and DF(v=1). The characterization of (DF)n and its effect upon these studies are discussed in detail. Measurements in undiluted DF were also performed at 200 and 296°K. The room temperature results clearly indicate a slower DF self-quenching rate than measured in DF–argon mixtures. This relaxation time lengthening can be explained by assuming that vibrational and rotational relaxation occurs on a similar time scale in undiluted DF.