A dual-polarized system fully implemented in substrate integrated technology is presented. It comprises an Orthomode Transducer (OMT) with planar excitation schemes for both orthogonal TE10 and TE01 modes and a dual-polarized horn antenna. The whole structure requires only 2 layers of substrate and it is based on the Extended Substrate Integrated Waveguide (ESIW), which allows the propagation of TEm0 and TE0n modes. A compact OMT design is proposed along with a procedure to optimize it. The matching and radiation characteristics of a dual-polarized horn antenna fed with this OMT are also studied. The complete structure was manufactured exhibiting an 8.6% bandwidth (13.9-15.15 GHz) where both modes are well matched (< -10 dB) and isolated (> 28 dB). The horn radiation patterns within the frequency range of operation are also similar for both polarizations. The proposed design demonstrates the feasibility of dualpolarized Substrate Integrated Circuits (SICs). This opens the door to new substrate integrated devices as well as to the use of SICs in applications requiring polarization diversity at endfire. All together, this combined design becomes a promising approach to tackle the increasing demand for capacity in modern communication systems.