Mathur, who is presently Special Secretary in Information and Broadcasting Ministry, will taker ove the new charge on Monday, an order issued by Department of Personnel and Training said.
He has been appointed in place of S M Vijayanand, who was last month sent back to his cadre state - Kerala - before completion of his tenure.
The competent authority has approved assignment of additional charge of the post of Secretary, Department of Rural Development, to Mathur for a period of one month or till the appointment of regular incumbent, it said.