diff --git a/Changelog.md b/Changelog.md
index e04d9fe..645822d 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,7 +1,9 @@
 # Changelog
 
 ## v0.4 - 24th February 2019 (unreleased)
- - [API] Added new `format` GET parameter to `device-data` action.
+ - [API] Added new `format` GET parameter to the following actions:
+     - `device-data`
+     - `list-reading-types`
 
 ## v0.3.3 - 20th February 2019
  - Updated to use new database structure
diff --git a/README.md b/README.md
index 9af005e..a0ae652 100644
--- a/README.md
+++ b/README.md
@@ -123,6 +123,7 @@ Examples:
 Parameter			| Type		| Meaning
 --------------------|-----------|---------------------
 `device-id`         | int		| Optional. If specified, this filters the list of measurement types to list only those reported by the device with the specified id.
+`format`            | string    | Optional. Specifies the format that the response will be returned in. Valid values: `json`, `csv`. Default: `json`.
 
 ```
 https://example.com/path/to/api.php?action=list-reading-types
@@ -153,7 +154,7 @@ Parameter			| Type		| Meaning
 `start`				| datetime  | The starting datetime.
 `end`				| datetime  | The ending datetime.
 `average-seconds`	| int		| Optional. If specified, readings will be grouped into lumps of this many seconds and averaged. For example a value of 3600 (1 hour) will return 1 data point per hour, with the value of each point an average of all the readings for that hour.
-`format`            | string    | Optional. Specifies the format that the response will be returned in. Valid values: `json`, `csv`. Default: `json`
+`format`            | string    | Optional. Specifies the format that the response will be returned in. Valid values: `json`, `csv`. Default: `json`.
 
 
 ### changelog
diff --git a/lib/SBRL/ResponseEncoder.php b/lib/SBRL/ResponseEncoder.php
new file mode 100644
index 0000000..31df56f
--- /dev/null
+++ b/lib/SBRL/ResponseEncoder.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace SBRL;
+
+/**
+ * Serialises an object to a variety of formats.
+ */
+class ResponseEncoder
+{
+	/**
+	 * Encodes an array of associative arrays to CSV.
+	 * @param	array	$data	The data to encode.
+	 * @return	string	The data encoded to csv.
+	 */
+	public static function encode_csv($data) {
+		if(empty($data))
+			return "";
+		
+		$result = fopen('php://temp/maxmemory:'. (5*1024*1024), 'r+');
+		fputcsv($result, array_keys($data[0]));
+		foreach($data as $row)
+			fputcsv($result, array_values($row));
+		rewind($result);
+		
+		$response = \stream_get_contents($result);
+		
+		fclose($result);
+		
+		return $response;
+	}
+}
diff --git a/logic/Actions/DeviceData.php b/logic/Actions/DeviceData.php
index d40812b..e029a3a 100644
--- a/logic/Actions/DeviceData.php
+++ b/logic/Actions/DeviceData.php
@@ -3,6 +3,7 @@
 namespace AirQuality\Actions;
 
 use \SBRL\TomlConfig;
+use \SBRL\ResponseEncoder;
 use \AirQuality\Repositories\IMeasurementDataRepository;
 use \AirQuality\Repositories\IMeasurementTypeRepository;
 use \AirQuality\ApiResponseSender;
@@ -117,17 +118,10 @@ class DeviceData implements IAction {
 				$response = json_encode($data);
 				break;
 			case "csv":
-				$result = fopen('php://temp/maxmemory:'. (5*1024*1024), 'r+');
-				fputcsv($result, array_keys($data[0]));
-				foreach($data as $row)
-					fputcsv($result, array_values($row));
-				rewind($result);
-				
 				$response_type = "text/csv";
 				$response_suggested_filename .= ".json";
-				$response = \stream_get_contents($result);
+				$response = ResponseEncoder::encode_csv($data);
 				
-				fclose($result);
 				break;
 		}
 		
@@ -135,7 +129,7 @@ class DeviceData implements IAction {
 		// 4: Send response
 		header("content-length: " . strlen($response));
 		header("content-type: $response_type");
-		header("content-disposition: inline; filename=data.csv");
+		header("content-disposition: inline; filename=$response_suggested_filename");
 		header("x-time-taken: " . PerfFormatter::format_perf_data($start_time, $start_handle, $start_encode));
 		echo($response);
 		return true;
diff --git a/logic/Actions/ListReadingTypes.php b/logic/Actions/ListReadingTypes.php
index 62444c5..20fd329 100644
--- a/logic/Actions/ListReadingTypes.php
+++ b/logic/Actions/ListReadingTypes.php
@@ -3,6 +3,7 @@
 namespace AirQuality\Actions;
 
 use \SBRL\TomlConfig;
+use \SBRL\ResponseEncoder;
 use \AirQuality\Repositories\IMeasurementTypeRepository;
 use \AirQuality\ApiResponseSender;
 
@@ -33,6 +34,13 @@ class ListReadingTypes implements IAction {
 		
 		// 1: Parse & validate parameters
 		$device_id = !empty($_GET["device-id"]) ? intval($_GET["device-id"]) : null;
+		$format = $_GET["format"] ?? "json";
+		if(!in_array($format, ["json", "csv"])) {
+			$this->sender->send_error_plain(406,
+				"Error: The format '$format' isn't recognised. Valid formats: " . implode(", ", $format) . "."
+			);
+			exit;
+		}
 		
 		// 1: Pull data from database
 		$data = null;
@@ -52,7 +60,19 @@ class ListReadingTypes implements IAction {
 		
 		// 3: Serialise data
 		$start_encode = microtime(true);
-		$response = json_encode($data);
+		$response = null;
+		$response_type = "application/octet-stream";
+		$response_suggested_filename = "data-" . date(\DateTime::ATOM) . "";
+		switch($format) {
+			case "json":
+				$response_type = "application/json";
+				$response = json_encode($data);
+				break;
+			case "csv":
+				$response_type = "text/csv";
+				$response = ResponseEncoder::encode_csv($data);
+				break;
+		}
 		
 		// 4: Send response
 		
@@ -60,7 +80,8 @@ class ListReadingTypes implements IAction {
 		// TODO: Investigate adding a short-term (~10mins?) cache-control header here
 		
 		header("content-length: " . strlen($response));
-		header("content-type: application/json");
+		header("content-type: $response_type");
+		header("content-disposition: inline; filename=$response_suggested_filename");
 		header("x-time-taken: " . PerfFormatter::format_perf_data($start_time, $start_handle, $start_encode));
 		echo($response);
 		return true;