Jicama (Pachyrhizus erosus L.) is a root‐based legume that has been cultivated in Mexico for centuries. Pectic polysaccharide from de‐starched jicama pomace was extracted using an autoclave‐assisted process and physicochemically characterized. The extracted polysaccharide (1.0 g L−1) was used for the formation of polyelectrolyte complexes (PECs) with water‐soluble chitosan (WSCh; 0.5, 1.0 and 2.0 g L−1). The extraction yield of jicama pectic polysaccharide was 22.8 wt% (dry basis) and infrared spectroscopic analysis showed that it was methoxylated to a small degree. Thermogravimetric analysis indicated that this biopolymer was very stable, its weight loss being 51.2% after heating at 479 °C. Anion‐exchange chromatography showed it to have a wide and heterogeneous charge density. The yield of the PECs was dependent on the concentration of WSCh used, it being 13.3, 26.7 and 18.3% with WSCh at 0.5, 1.0 and 2.0 g L−1, respectively. The PECs had higher thermostability compared with WSCh and this confirmed the complex formation between WSCh and jicama polysaccharide. WSCh is a promising polycation able to interact with low‐methoxylated pectic polysaccharide from jicama to produce PECs with uses in a wide variety of specialized applications such as food technology and medicine. Copyright © 2011 Society of Chemical Industry A polyelectrolyte complex was formed as a result of the interaction between pectic polysaccharide from jicama and water‐soluble chitosan (20 kg mol−1).