diff --git a/docs/docs/configuration/client.rst b/docs/docs/configuration/client.rst
index 6b91e77..1829b69 100644
--- a/docs/docs/configuration/client.rst
+++ b/docs/docs/configuration/client.rst
@@ -51,8 +51,12 @@ Defaults to `true`.
 data-isso-lang
 --------------
 
-Override useragent's preferred language. Currently available: german (de),
-english (en), french (fr), italian (it), esperanto (eo), russian (ru) and spanish (es).
+Override useragent's preferred language. Isso has been translated in over 12
+languages. The language is configured by its `ISO 639-1
+<https://en.wikipedia.org/wiki/ISO_639-1>`_ (two letter) code.
+
+You find a list of all supported languages on `GitHub
+<https://github.com/posativ/isso/tree/master/isso/js/app/i18n>`_.
 
 data-isso-reply-to-self
 -----------------------
diff --git a/isso/js/app/i18n.js b/isso/js/app/i18n.js
index 010d966..f13b324 100644
--- a/isso/js/app/i18n.js
+++ b/isso/js/app/i18n.js
@@ -1,9 +1,10 @@
-define(["app/config", "app/i18n/de", "app/i18n/en", "app/i18n/fr", "app/i18n/ru", "app/i18n/it", "app/i18n/eo", "app/i18n/sv", "app/i18n/nl", "app/i18n/el_GR", "app/i18n/es", "app/i18n/zh_CN"], function(config, de, en, fr, ru, it, eo, sv, nl, el, es, zh) {
+define(["app/config", "app/i18n/cs", "app/i18n/de", "app/i18n/en", "app/i18n/fr", "app/i18n/ru", "app/i18n/it", "app/i18n/eo", "app/i18n/sv", "app/i18n/nl", "app/i18n/el_GR", "app/i18n/es", "app/i18n/zh_CN"], function(config, cs, de, en, fr, ru, it, eo, sv, nl, el, es, zh) {
 
     "use strict";
 
     var pluralforms = function(lang) {
         switch (lang) {
+        case "cs":
         case "de":
         case "el":
         case "en":
@@ -44,6 +45,7 @@ define(["app/config", "app/i18n/de", "app/i18n/en", "app/i18n/fr", "app/i18n/ru"
     }
 
     var catalogue = {
+        cs: cs,
         de: de,
         el: el,
         en: en,
diff --git a/isso/js/app/i18n/cs.js b/isso/js/app/i18n/cs.js
new file mode 100644
index 0000000..77e6401
--- /dev/null
+++ b/isso/js/app/i18n/cs.js
@@ -0,0 +1,27 @@
+define({
+    "postbox-text": "Sem napiště svůj komentář (nejméně 3 znaky)",
+    "postbox-author": "Jméno (nepovinné)",
+    "postbox-email": "E-mail (nepovinný)",
+    "postbox-website": "Web (nepovinný)",
+    "postbox-submit": "Publikovat",
+    "num-comments": "Jeden komentář\n{{ n }} Komentářů",
+    "no-comments": "Zatím bez komentářů",
+    "comment-reply": "Odpovědět",
+    "comment-edit": "Upravit",
+    "comment-save": "Uložit",
+    "comment-delete": "Smazat",
+    "comment-confirm": "Potvrdit",
+    "comment-close": "Zavřít",
+    "comment-cancel": "Zrušit",
+    "comment-deleted": "Komentář smazán",
+    "comment-queued": "Komentář ve frontě na schválení",
+    "comment-anonymous": "Anonym",
+    "comment-hidden": "{{ n }} skryto",
+    "date-now": "právě teď",
+    "date-minute": "před minutou\npřed {{ n }} minutami",
+    "date-hour": "před hodinou\npřed {{ n }} hodinami",
+    "date-day": "včera\npřed {{ n }} dny",
+    "date-week": "minulý týden\npřed {{ n }} týdny",
+    "date-month": "minulý měsíc\npřed {{ n }} měsíci",
+    "date-year": "minulý rok\npřed {{ n }} lety"
+});