See code:

from pandas_datareaders.datareaders.base import DataReaderBase
import pandas as pd
import json
from StringIO import StringIO
dr = DataReaderBase(expire_after=60*60)
BASE_URL = 'http://openexchangerates.org/api'
endpoint = '/latest.json'
url = BASE_URL + endpoint
params = {
    'app_id': ''
}
response = dr.session.get(url, params=params)
raw_data = response.text # or .content if binary data is expected
data = json.loads(raw_data)
...