Yes, a demat account is required for investing in ETFs. You can place a buy order from your trading account. During the settlement process, your trading/bank account will be debited with the transaction amount, and the ETF units will be credited to your demat account. For selling ETF units, you have to place the sell order from your trading account. During the settlement process, the ETF units will be debited from your demat account, and your bank/trading account will be credited with the transaction amount.