BUENOS AIRES, Oct 10 (Reuters) - The power generation

unit of Argentine state oil firm YPF said on Thursday

it was placing an 8-year $420 million bond, with proceeds from

the issuance to be used to pay back a 2019 bond worth $400

million.

"Investors' support has allowed us to achieve one of the

lowest rates in the Argentine market and to substantially

improve the company's debt profile," Martin Mandarano, the

unit's chief executive, said in a statement.