not sure if it is OHLC:
http://api.bitcoincharts.com/v1/csv/edit:
https://poloniex.com/support/api/and you can get it directly from poloniex API, but lowest period is 300 seconds:
returnChartData
Returns candlestick chart data. Required GET parameters are "currencyPair", "period" (candlestick period in seconds; valid values are 300, 900, 1800, 7200, 14400, and 86400), "start", and "end". "Start" and "end" are given in UNIX timestamp format and used to specify the date range for the data returned. Sample output:
[{"date":1405699200,"high":0.0045388,"low":0.00403001,"open":0.00404545,"close":0.00427592,"volume":44.11655644,
"quoteVolume":10259.29079097,"weightedAverage":0.00430015}, ...]
Call:
https://poloniex.com/public?command=returnChartData¤cyPair=BTC_XMR&start=1405699200&end=9999999999&period=14400