The company had sold 39,807 units in June 2016, HMIL said in a statement.
In January-June, the domestic sales figure for the automaker stood at 2,53,428 units, up 4.1 per cent from 2,43,442 in the year-ago period.
HMIL Director Sales and Marketing Rakesh Srivastava said: "In a challenging market fuelled with speculations on the GST tax structure, Hyundai registered highest-ever half-year domestic sales on account of strong acceptance brands Grand i10, Elite i20 and Creta in pre-GST business environment."
The company expects a positive demand pull, post successful implementation of GST, in coming months as the industry will witness heightened level of customer interest in a seamless and unified single market, he added.