IIT Madras M.Tech Admission is offered on the basis of GATE score.

As you want to do M.tech from IIT Chennai and asking for admission process dates , so I am telling all key dates here :

Key dates
Opening of Website for ONLINE applications 07 Mar 2016
Closing of Website for ONLINE applications 15 Apr 2016
Suitability Test/ Interview for relevant candidates (for GATE & IIT Candidates) 30 Apr 2016
Written Test and/or Interview (for sponsored candidates only) 02 ,03 Jun 2016
Date of reporting for admission 25 Jul 2016
Date for Additional Round after the Admission Day (only if
there are any unfilled seats) 26 Jul 2016
Orientation Programme, Photo session and Workflow
Enrolment 27 Jul 2016
Commencement of Classes 01 Aug 2016

Eligibiliy Criteria
Students must have bachelor’s degree in Engineering/ Technology/ Architecture from educational Institutions approved by AICTE/ Government.
Master’s degree in Chemistry/ Life Sciences/ Mathematics/ Physics related subjects from educational Institutions approved by UGC/ Government.

Address

Indian Institute of Technology Madras
Beside Adyar Cancer Institute
Opposite to C.L.R.I
Sardar Patel Road, Adyar
Chennai, Tamil Nadu 600036