Friedel-Crafts alkylation and acylation reactions using highly polluting homogeneous Lewis and Bronsted acids, are ubiquitous in a variety of organic process industries. In many cases very high conversions and selectivities can be achieved with aluminum chloride as catalyst and nitrobenzene as a solvent. However, environmental concerns associated with aluminum chloride-nitrobenzene or BF3-HF or mineral acids catalysts have encouraged development of solid acids, which not only intensify the rates of reactions but also offer better product selectivity. Amongst these catalysts, sulfated zirconia has gained a considerable importance due to its super-acidity under certain conditions. The alkylation of diphenyl oxide with 1-decene was studied over sulfated zirconia catalyst and it leads to industrially important products. The surface reaction between chemisorbed 1-decene diphenyl oxide from the liquid phase, in the absence of any mass transfer resistance, was found to be the rate determining step with Eley-Rideal type of mechanism.