Mendelski has represented Poland in both the K-1 200 m and 500 m, but specialises in the former discipline, the shortest race-distance. He also competed in two Summer Olympics, earning his best finish of sixth in the K-4 1000 m event at Beijing in 2008. He is 178 cm (5 ft 10 in) tall and weighs 88 kg (194 lbs).
At the world championships he finished sixth (2001), fourth (2002) and sixth (2003) before finally making the podium at the 2005 worlds in Zagreb, Croatia, where he won the silver medal. He also won the bronze medal at the 2004 European Championships in Poznań, Poland, finishing just in front of Spain"s Jovino González. Mendelski also won two silver medals in the K-4 1000 m event at the International Coach Federation Canoe Sprint World Championships, earning them in 2006 and 2007, and a bronze in the K-4 500 m event at 2006.
"Tomaj" is a member of the OKS Olstyn Canoe Club.
