At 2012 Summer Olympics in London, Maslák competed in the 200 and 400 m events. In the 400 metres, he advanced from heats by setting a new national record and personal best of 44.91 but did not manage to repeat the feat in semi-finals and finished fifth in his run. In the 200 metres, Maslák finished fourth in Heat 5 in a time of 20.67 and did not progress further. In his last race of the 2012 season, Maslák set a national record of 20.59 in 200 metres dash.