Boiling points (T-B) of acyclic monochloroalkanes are predicted from their boiling point numbers (YBP) with the relationship previously established for hydrocarbons, T-B (K) = -16.802 Y-BP(2/3) + 337.377 Y-BP(1/3) 437.883. The Y-BP values are determined from molecular structure through the relationship Y-BP = 1.726 + I-Cl + 2.779C + 1.716M(3) + 1.564M + 4.204E(3) + 3.905E 0.329D + 0.241G + 0.479V + 0.574S. Here I-Cl is a contribution to the Y-BP value resulting from the substitution of Cl for H on an alkane, while the other parameters are the same as those reported earlier for calculating Y-BP values of alkanes. For a data set of 82 acyclic monochloroalkanes having from 4 to 20 carbon atoms, the average absolute deviation between reported T-B values and those predicted with these equations was 1.39 K, and the R-2 of the correlation was 0.999. In addition, the calculated Y-BP values provide a useful means to predict the flash points of monochloroalkanes through the relationship T-FP (K) = 150.5 ln(Y-BP) - 185.6.