from pandas import DataFrame
t = {'time': ['08:35', '08:38', '13:42', '13:46']}
df = DataFrame(t)

import numpy as np
time_array = np.array(df.time)
print time_array

['08:35' '08:38' '13:42' '13:46']

for i in range(len(time_array)):
    print np.fromstring(time_array[i], dtype=int, sep=":")

[ 8 35]
[ 8 38]
[13 42]
[13 46]

def foo(array):
    for i in range(len(array)):
        array[i] = np.fromstring(array[i], dtype=int, sep=':')

%timeit foo(time_array)

def foo2(df):
    df['hour'] = df['time'].apply(lambda x: int(x.split(':')[0]))
    df['minute'] = df['time'].apply(lambda x: int(x.split(':')[1]))

%timeit foo2(df)

import time
def foo3(df):
    df['hour'] = df['time'].apply(lambda x: time.strptime(x, '%H:%M').tm_hour)
    df['minute'] = df['time'].apply(lambda x: time.strptime(x, '%H:%M').tm_min)

%timeit foo3(df)

from pandas import DataFrame
t = {'time': ['08:35', '08:38', '13:42', '13:46']}
df = DataFrame(t)
df['hour'] = df['time'].apply(lambda x: int(x.split(':')[0]))
df['minute'] = df['time'].apply(lambda x: int(x.split(':')[1]))
print(df)

    time  hour  minute
0  08:35     8      35
1  08:38     8      38
2  13:42    13      42
3  13:46    13      46

import time
df['hour'] = df.timestring.apply(lambda x: time.strptime(x, '%H:%M').tm_hour)
df['minute'] = df.timestring.apply(lambda x: time.strptime(x, '%H:%M').tm_min)