diff --git a/prizm.cabal b/prizm.cabal
--- a/prizm.cabal
+++ b/prizm.cabal
@@ -1,5 +1,5 @@
 Name:                prizm
-Version:             0.1.0.3
+Version:             0.1.0.4
 Synopsis:            A haskell library for computing with colors
 
 Description:         Prizm can convert between many different color
@@ -43,7 +43,8 @@
   
   ghc-options: -Wall
   
-  build-depends: base ==4.5.*
+  build-depends: base ==4.5.*,
+                 text >= 0.11.2.3
 
 test-suite tests
   type:           exitcode-stdio-1.0
diff --git a/src/Data/Prizm/Color/SRGB.hs b/src/Data/Prizm/Color/SRGB.hs
--- a/src/Data/Prizm/Color/SRGB.hs
+++ b/src/Data/Prizm/Color/SRGB.hs
@@ -2,12 +2,21 @@
 (
   toXYZ
 , toXYZMatrix
+, toHex
+, fromHex
 ) where
 
+import Numeric (showHex)
+
+import Data.Monoid
 import Data.Prizm.Types
 import Data.Prizm.Color.Transform
 import Data.Prizm.Color.Matrices.RGB
 
+import Data.String
+import qualified Data.Text as T
+import Data.Text.Read as R
+
 import Control.Applicative
 
 -- | @rgbTransform@ transform an RGB integer to be computed against
@@ -18,12 +27,51 @@
     where dv = fromIntegral v / 255
           ap = 1.0 + 0.055
 
+-- | @toHex@ convert an sRGB value to hexadecimal.
+toHex :: RGB Integer -> Hex
+toHex = showRGB
+
+fromHex :: Hex -> RGB Integer
+fromHex = parse . fromString
+
+parse :: T.Text -> RGB Integer
+parse t =
+  case T.uncons t of
+    Just ('#', cs) | T.all isHex cs ->
+      case T.unpack cs of
+        [a, b, c, d, e, f, _g, _h] -> RGB (hex a b) (hex c d) (hex e f)
+        [a, b, c, d, e, f      ]   -> RGB (hex a b) (hex c d) (hex e f)
+        [a, b, c, _d            ]  -> RGB (hex a a) (hex b b) (hex c c)
+        [a, b, c               ]   -> RGB (hex a a) (hex b b) (hex c c)
+        _                          -> err
+    _                              -> err
+
+  where
+    hex a b = either err fst (R.hexadecimal (T.singleton a <> T.singleton b))
+    isHex a = (a >= 'a' && a <= 'f') || (a >= 'A' && a <= 'F') || (a >= '0' && a <= '9')
+    err     = error "Invalid color string"
+
 -- | @toXYZ@ convert an sRGB value to a CIE XYZ value.
 toXYZ :: RGB Integer -> CIEXYZ Double
 toXYZ = (toXYZMatrix d65SRGB)
 
 toXYZMatrix :: RGBtoXYZ -> RGB Integer -> CIEXYZ Double
 toXYZMatrix m (RGB r g b) =
-    let t = ZipList (transform <$> [r,g,b])
+    let t = ZipList (transform <$> (clamp <$> [r,g,b]))
         [x,y,z] = (roundN 3) <$> ((zipTransform t) <$> m)
     in CIEXYZ x y z
+
+clamp :: Integer -> Integer
+clamp i = max (min i 255) 0
+
+{- All credit for the below three functions go to the HSColour
+   module-}
+
+-- |Show a colour in hexadecimal form, e.g. \"#00aaff\"
+showRGB :: RGB Integer -> Hex
+showRGB c =
+  (("#"++) . showHex2 r' . showHex2 g' . showHex2 b') ""
+ where
+  RGB r' g' b' = c
+  showHex2 x | x <= 0xf = ("0"++) . showHex x
+             | otherwise = showHex x
diff --git a/src/Data/Prizm/Types.hs b/src/Data/Prizm/Types.hs
--- a/src/Data/Prizm/Types.hs
+++ b/src/Data/Prizm/Types.hs
@@ -5,6 +5,8 @@
 type RGBtoXYZ = [[Double]]
 type XYZtoRGB = [[Double]]
 
+type Hex = String
+
 data RGB a = RGB !a !a !a
     deriving (Eq, Ord, Show)
 
diff --git a/tests/QC/SRGB.hs b/tests/QC/SRGB.hs
--- a/tests/QC/SRGB.hs
+++ b/tests/QC/SRGB.hs
@@ -5,6 +5,8 @@
 import Test.Framework.Providers.QuickCheck2 (testProperty)
 import Test.QuickCheck
 
+import Numeric
+
 import Control.Monad
 
 import Data.Prizm.Color.SRGB as S
@@ -15,7 +17,9 @@
     arbitrary = liftM3 RGB (choose (0, 255)) (choose (0, 255)) (choose (0, 255))
 
 rgb2XYZ v = C.toRGB(S.toXYZ v) == v
+rgb2HEX v = S.fromHex(S.toHex v) == v
 
 tests = [
-    testProperty "SRGB <-> CIE XYZ" rgb2XYZ
+    testProperty "SRGB <-> CIE XYZ" rgb2XYZ,
+    testProperty "HEX <-> SRGB" rgb2HEX
       ]