The heat capacities at constant pressure of 1-chloropropane, 1-chlorobutane, 1-chloropentane, 1-chlorohexane, 1-chloroheptane, 1-chlorooctane, 1-chlorodecane, and 1-bromoalkanes (1-bromoethane, 1-bromopropane, 1-bromobutane, 1-bromopentane, 1-bromohexane, 1-bromoheptane, 1-bromononane, and 1-bromodecane) were measured within the temperature range from 284 K to 353 K by a DSC III (Setaram) differential scanning calorimeter. These data and data previously reported for alpha-,omega-dibromoalkanes and alpha,omega-dichloroalkanes, have been used as input for a group additivity type analysis. The C-P group contributions as a function of temperature of the CH3 and CH2 groups and Cl and Br atoms were determined by the group additivity analysis (GAA) method. A molecular connectivity model (MCI) for the calculation of the molar heat capacities of halogenoalkanes is also presented. The given model is based on a set of six molecular connectivity indexes, MCI = {D, D-v, X-0, X-0(v), X-1, X-1(v)}. The merits of the additivity scheme are discussed.