diff --git a/profile.d/help.sh b/profile.d/help.sh
index 8fed25e..5f9854c 100644
--- a/profile.d/help.sh
+++ b/profile.d/help.sh
@@ -72,6 +72,7 @@ help()
     printf "   * setc\tSet locale to standard C (POSIX)\n"
     printf "   * set*\tLocale shortcuts generated from SET_LOCALE in profile.conf\n"
     printf "settrace\tActivate or deactivate ERR trap to display backtrace on script errors\n"
+    printf "set_theme\tSwitch the prompt colour theme; no argument lists available themes\n"
     printf "showinfo\tDisplay welcome banner and system information (figlet + neofetch/fastfetch)\n"
     printf "ssr\t\tSSH into a server as root, forwarding extra ssh options\n"
     printf "taz\t\tCompress files and directories into a chosen archive format\n"
diff --git a/profile.d/prompt.sh b/profile.d/prompt.sh
index 99bc44d..d9312f2 100644
--- a/profile.d/prompt.sh
+++ b/profile.d/prompt.sh
@@ -164,6 +164,46 @@ load_theme()
         fi
     done < "$theme_file"
 }
+# Not exported, it remains private
+# ------------------------------------------------------------------------------
+
+
+# ------------------------------------------------------------------------------
+# Dynamically switch the prompt theme for the current shell session.
+# Calls load_theme to apply the new colour values immediately, then updates
+# PROMPT_THEME so subshells and the set_prompt fallback chain reflect the
+# change.  PROMPT_THEME_DIR is honoured when set.
+# Usage: set_theme [theme_name_or_path]
+#   With no argument (or -l / --list), lists available .theme files.
+set_theme()
+{
+    local theme_dir="${PROMPT_THEME_DIR:-${MYPATH}/profile.d/themes}"
+
+    # -- list mode -----------------------------------------------------------
+    if [[ $# -eq 0 || "$1" == "-l" || "$1" == "--list" ]]; then
+        printf "Available themes in %s:\n" "$theme_dir"
+        local f name
+        for f in "$theme_dir"/*.theme; do
+            [[ -f "$f" ]] || continue
+            name="${f##*/}"
+            name="${name%.theme}"
+            if [[ "$name" == "${PROMPT_THEME:-}" ]]; then
+                printf "  * %s (active)\n" "$name"
+            else
+                printf "    %s\n" "$name"
+            fi
+        done
+        return 0
+    fi
+
+    # -- apply mode ----------------------------------------------------------
+    local theme_name="$1"
+    load_theme "$theme_name" || return 1
+
+    export PROMPT_THEME="$theme_name"
+    disp I "Prompt theme set to $theme_name."
+}
+export -f set_theme
 # ------------------------------------------------------------------------------