The circular economy promotes the recycling of plastics to develop new materials and products. The blends of immiscible plastics increase the availability of materials. An Ecuadorian company brought these researchers some amount of unknown blends of recycled high-density polyethylene (rHDPE) and recycled polypropylene (rPP). The quantification of the rHDPE and rPP helps us optimize the amount of compatibilizer, which gives us the possibility of transforming them into a new material with specific properties. The effects of Polypropylene-based Olefin Block Copolymer (Intune) and Organoclay (Cloisite 20A) on the structure and the thermo-mechanical properties of the rHDPE and rPP blends were investigated in a three-phased experimental project. Phase one required the identification of the amount of both plastic materials; a series of known compositions of both plastics was obtained by melting and mixing the HDPE and PP in a torque rheometer. A calibration curved (Enthalpy vs. wt% Polymer) for each polymer was generated through Differential Scanning Calorimetry (DSC). In Phase two, the optimized amount of compatibilizer was incorporated in the known recycled plastics blend. Whereas, in phase three a compression molding was used to obtain several samples sizes to study the morphology via x-ray diffraction, rheological properties by means of a plate-plate rheometer, flexural properties and thermal properties through DSC/TGA. A protocol was developed for the company, so they can adjust either the amount of recycled plastics or the compatibilizer to meet required properties.