The dynamic viscosity eta and the density rho of heptylbenzene (1-phenylheptane) and heptylcyclohexane (1-cyclohexylheptane) have been studied as a function of temperature (293.15 K to 353.15 K in 10 K steps) and pressure (up to 60 MPa for density and up to 100 MPa for viscosity). The dynamic viscosity was measured with a falling-body viscometer, except at atmospheric pressure, where a classical capillary viscometer was used. The uncertainty for the viscosity is less than 2%. The uncertainty in the density measurements is less than 1 kg(.)m(-3). Using a Tait-type relation, the density has been extrapolated to 80 and 100 MPa. The dynamic viscosities of these two compounds have been modeled with three recently proposed models which have a physical and theoretical background but represent three different approaches. The models considered are the hard-sphere viscosity scheme, the free-volume viscosity model, and the friction theory. For these three models, the absolute average deviation is of the order of the experimental error.