The per capita income in India being Rs. 20 in 1867-68 was ascertained for the first time by Dadabhai Naoroji.

Dadabhai Naoroji, often referred to as the Grand Old Man of India, was an Indian political leader, social reformer, and economist. He is known for his extensive work on the economic condition of India under British colonial rule. In his book "Poverty and Un-British Rule in India," published in 1901, he analyzed various economic factors and estimated the per capita income of India during different periods.

Naoroji`s research and analysis provided valuable insights into the economic exploitation of India by the British and the impoverishment of its people. His work played a significant role in raising awareness about India`s economic conditions and advocating for economic reforms.

Therefore, it was Dadabhai Naoroji who first ascertained the per capita income in India as Rs. 20 in 1867-68.