The objective of this work is to study, for the first time, the photodegradation of 4-chlorophenol (4CP) catalyzed by a calcined Mg-Zn-Al layered double hydroxides (MgAlZn LDHs) in a co-current downflow bubble column (CDBC) photoreactor at pilot scale. The effect of initial organic compound concentration (C-4CP0), temperature (T), and mass catalyst over reaction rate (-r(4CP)) was elucidated. An intrinsic kinetic regime was established, and a single-site Langmuir-Hinshelwood mechanism was determined to occur during the organic compound oxidation. The catalyst was characterized by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), and ultraviolet visible light (UV/vis) spectrophotometry. The reaction progress was verified by UV/vis spectrophotometry and total organic carbon (TOC) content. Degradation and mineralization rate were found to be dependent on T and 4CP concentration. In the range of studied operating conditions, a maximum of 94% 4CP was degraded, while 70% total organic carbon removal was achieved.