The base idea of co-simulation is to couple heterogeneous simulators in a single environment. This allows for choosing the best-suited simulator to represent each part of a complex system. Hardware-in-the-loop co-simulation introduces physical components in a software co-simulation. In this paper, we propose a hardware-in-the-loop co-simulation platform using a dynamically reconfigurable architecture on FPGAs. Main uses for this technology include introducing prototypes of digital systems directly in the simulation environment, and accelerating simulation by using FPGAs to implement models that can take advantage of parallelism. The platform was validated by coupling a C++ application with hardware modules loaded on-demand on a FPGA.