Can I buy shares on record date to be eligible for rights issue?

No, you will not be eligible for the rights issue if you buy the shares on the record date.

A person needs to be on the record of the company as on record date to qualify as an eligible shareholder. If you buy the shares on the record date, the shares will get credited to your Demat account on T+2 and thus you will not own shares of the company as on record date. Thus you should buy the shares two days before the record date to be eligible for the rights issue.

For example, if a company fixes 28th August as the record date, you should buy the shares latest by or before and not later than 26th August so that you receive the credit of shares in your Demat account by 28th August to qualify for the rights issue.