Fouling of heat exchangers in energy and power plant industry, oil and gas industry, pharmaceutical and food process industry, industrial waste heat recovery is a major problem which needs to be solved urgently. In the United Arab Emirates, a majority of oil & gas processing plants are located in the desert where water accessibility is limited, thus fin-fan type of heat exchangers are used for cooling and/or heating applications. Such harsh environments cause external fouling which becomes an unavoidable problem in these heat exchangers. With increased humidity and high process temperatures, the dust particulates start to stick on the outer surface of heat exchangers which drastically reduces the thermal performance and increases power consumption. In order to identify possible methods to control and/or eliminate such kinds of external fouling, it is important to identify the composition and morphology of such foulants. This study presents the characterization of selected fouling samples collected from several fin-fan type air cooled heat exchangers taken from a gas processing plant. Scanning electron microscope (SEM) tests were carried out to determine the physical characteristics of sample foulant. Variability in sizes and shapes was found between samples due, perhaps, to different working temperature ranges of the selected heat exchangers. X-ray diffraction (XRD) analyses revealed presence of quartz, calcite, and alumina with traces of halite and hematite. Laser flash analysis (LFA) was conducted to quantify the specific heat capacity, thermal diffusivity and thermal conductivity of the fouling samples. The diversity of these fouling samples reflects complexity with respect to their potential removal and effects on heat transfer characteristics. Though, this research work is a case study for a specific petrochemical plant, however, findings in this study can be adopted by other industries involved in similar chemical processing in the Middle East as well as other countries having similar weather and geological conditions.