We performed an initial evaluation of a state-of-the-art commercial preclinical PET/CT scanner (SuperArgus 4R, SEDECAL, Madrid, Spain). The PET unit consists of 4 rings of 96 detector modules each with an array of 338 1.45 × 1.45 × 15 mm3 pixelated LYSO and GSO phoswich crystals with DOI information. It has a maximum axial FOV of 100 mm and transaxial FOV of 120 mm. The CT unit consists of an x-ray source with variable micro focal spot size and a large 229 × 145 mm2 flat-panel detector that allows imaging of a volume-of-view (VOV) at three different magnifications, at a smallest voxel of 15 micron. We measured the sensitivity and uniformity of the PET unit using a calibrated Na-22 point source and a cylindrical phantom filled with a homogeneous FDG solution. The system resolution was determined from the reconstructed images of a thin FDG-filled capillary tube in air and inside a plastic cylinder, and a hot-rod phantom using the FBP and the 3D iterative reconstruction algorithm at different iteration numbers. The uniformity of the CT unit was evaluated from a summed reconstructed image with low statistical image noise of and at three magnifications. The resolution was determined from the edge functions of images of a set of precision-machined acrylic rods of different diameters at three magnifications and with different acquired and reconstructed pixel sizes. The dual-modality image co-registration was assessed using a set of CT and PET images obtained from a phantom consisting of a Ge-68 annulus ring phantom with an attached Na-22 point source. Finally, the preclinical imaging performance of the PET/CT system were evaluated from sample images several small animal studies. Our preliminary results showed the PET unit was able to achieve a system resolution of 0.85 mm and sensitivity of ∼8.9 %, and the CT unit a highest resolution of ∼20 micron. We conclude the preclinical PET/CT system meet the stated specifications and is suitable for high performance preclinical molecular imaging of small animals.