My contract with a Kolkata firm has an arbitration clause; how do I start arbitration?

You can invoke the arbitration clause by sending a notice under Section 21 of the Arbitration and Conciliation Act, 1996 to the other party, proposing arbitrator(s) and the seat. If the other party fails to respond, you can approach Calcutta High Court under Section 11 for appointment of an arbitrator. The tribunal conducts the proceedings, and the award is enforceable as a decree under Section 36, with challenge limited to Section 34 grounds. West Bengal Premises Tenancy Act 1997 does not override the central Act, but State commercial courts may handle arbitration-related applications. Domestic awards can be challenged within three months, and foreign awards enforced under Part II. Interim relief is available under Section 9 before or during arbitration. The seat determines the supervisory court.