For ASCII characters in the range [ -~] on Python 2:

>>> import binascii
>>> bin(int(binascii.hexlify('hello'), 16))
'0b110100001100101011011000110110001101111'

In reverse:

>>> n = int('0b110100001100101011011000110110001101111', 2)
>>> binascii.unhexlify('%x' % n)
'hello'

In Python 3.2+:

>>> bin(int.from_bytes('hello'.encode(), 'big'))
'0b110100001100101011011000110110001101111'

In reverse:

>>> n = int('0b110100001100101011011000110110001101111', 2)
>>> n.to_bytes((n.bit_length() + 7) // 8, 'big').decode()
'hello'

To support all Unicode characters in Python 3:

def text_to_bits(text, encoding='utf-8', errors='surrogatepass'):
    bits = bin(int.from_bytes(text.encode(encoding, errors), 'big'))[2:]
    return bits.zfill(8 * ((len(bits) + 7) // 8))

def text_from_bits(bits, encoding='utf-8', errors='surrogatepass'):
    n = int(bits, 2)
    return n.to_bytes((n.bit_length() + 7) // 8, 'big').decode(encoding, errors) or '\0'

Here's single-source Python 2/3 compatible version:

import binascii

def text_to_bits(text, encoding='utf-8', errors='surrogatepass'):
    bits = bin(int(binascii.hexlify(text.encode(encoding, errors)), 16))[2:]
    return bits.zfill(8 * ((len(bits) + 7) // 8))

def text_from_bits(bits, encoding='utf-8', errors='surrogatepass'):
    n = int(bits, 2)
    return int2bytes(n).decode(encoding, errors)

def int2bytes(i):
    hex_string = '%x' % i
    n = len(hex_string)
    return binascii.unhexlify(hex_string.zfill(n + (n & 1)))

Example

>>> text_to_bits('hello')
'0110100001100101011011000110110001101111'
>>> text_from_bits('110100001100101011011000110110001101111') == u'hello'
True

See String Formatting for what "%x" % string is doing.

Spoiler: It's where the hex comes from.

Use following one liner

x = chr(int('010101010',2))

will work.

Let's take the word 'hello' which is 0110100001100101011011000110110001101111

To translate that back to characters we can use chr and int (with a base of 2) and some list slicing...

''.join(chr(int(bin_text[i:i+8], 2)) for i in xrange(0, len(bin_text), 8))

If we wanted to take 'hello' and convert it to binary we can use ord and string formatting...

''.join('{:08b}'.format(ord(c)) for c in 'hello')

From your example, your input looks like a string of a binary formatted number.

If so, you don't need a dictionnary for that:

def byte_to_char(input):
     return chr(int(input, base=2))

Using the data you gave in the comments, you have to split your binary string into bytes.

input ='01010100011010000110100101110011001000000110100101110011001000000110101001110101011100110111010000100000011000010010000001110100011001010111001101110100001000000011000100110000001110100011000100110000'
length = 8
input_l = [input[i:i+length] for i in range(0,len(input),length)]

And then, per byte, you convert it into a char:

input_c = [chr(int(c,base=2)) for c in input_l]
print ''.join(input_c)

Putting it all together:

def string_decode(input, length=8):
    input_l = [input[i:i+length] for i in range(0,len(input),length)]
    return ''.join([chr(int(c,base=2)) for c in input_l])

decode(input)
>'This is just a test 10:10'