import xlrd
import os
from xlutils.copy import copy
from xlwt import Style

def writeExcel(row, col, str, styl=Style.default_style):
 rb = xlrd.open_workbook(file, formatting_info=True)
 wb = copy(rb)
 ws = wb.get_sheet(0)
 ws.write(row, col, str, styl)
 wb.save(file)

style = xlwt.easyxf('font:height 240, color-index red, bold on;align: wrap on, vert centre, horiz center');
writeExcel(1, 1, 'hello world', style) 

formatting_info=True

ws.write_merge(top_row, bottom_row, left_column, right_column, string)