diff --git a/spring-core/src/main/java/org/springframework/util/MimeType.java b/spring-core/src/main/java/org/springframework/util/MimeType.java
index 3c96f445e2ab..91373194ee8a 100644
--- a/spring-core/src/main/java/org/springframework/util/MimeType.java
+++ b/spring-core/src/main/java/org/springframework/util/MimeType.java
@@ -486,9 +486,9 @@ public boolean equals(@Nullable Object other) {
 	/**
 	 * Determine if the parameters in this {@code MimeType} and the supplied
 	 * {@code MimeType} are equal, performing case-insensitive comparisons
-	 * for {@link Charset Charsets} and disregarding quoting of parameter
-	 * values, so that, for example, {@code spring="framework"} and
-	 * {@code spring=framework} are considered equal.
+	 * for parameter names and {@link Charset Charsets}, and disregarding
+	 * quoting of parameter values, so that, for example, {@code spring="framework"}
+	 * and {@code spring=framework} are considered equal.
 	 * @since 4.2
 	 */
 	private boolean parametersAreEqual(MimeType other) {
@@ -501,7 +501,7 @@ private boolean parametersAreEqual(MimeType other) {
 			if (!other.parameters.containsKey(key)) {
 				return false;
 			}
-			if (PARAM_CHARSET.equals(key)) {
+			if (PARAM_CHARSET.equalsIgnoreCase(key)) {
 				if (!ObjectUtils.nullSafeEquals(getCharset(), other.getCharset())) {
 					return false;
 				}
@@ -528,15 +528,15 @@ public int hashCode() {
 
 	/**
 	 * Compute a hash code for the parameters map, consistent with
-	 * {@link #parametersAreEqual}: normalizing {@link Charset Charsets} and
-	 * disregarding quoting of parameter values.
+	 * {@link #parametersAreEqual}: normalizing parameter names and
+	 * {@link Charset Charsets}, and disregarding quoting of parameter values.
 	 */
 	private int parametersHashCode() {
 		int result = 0;
 		for (Map.Entry<String, String> entry : this.parameters.entrySet()) {
 			String key = entry.getKey();
-			Object value = (PARAM_CHARSET.equals(key) ? getCharset() : unquote(entry.getValue()));
-			result += key.hashCode() ^ ObjectUtils.nullSafeHashCode(value);
+			Object value = (PARAM_CHARSET.equalsIgnoreCase(key) ? getCharset() : unquote(entry.getValue()));
+			result += key.toLowerCase(Locale.ROOT).hashCode() ^ ObjectUtils.nullSafeHashCode(value);
 		}
 		return result;
 	}
@@ -602,7 +602,7 @@ public int compareTo(MimeType other) {
 			if (comp != 0) {
 				return comp;
 			}
-			if (PARAM_CHARSET.equals(thisAttribute)) {
+			if (PARAM_CHARSET.equalsIgnoreCase(thisAttribute)) {
 				Charset thisCharset = getCharset();
 				Charset otherCharset = other.getCharset();
 				if (thisCharset != otherCharset) {
diff --git a/spring-core/src/test/java/org/springframework/util/MimeTypeTests.java b/spring-core/src/test/java/org/springframework/util/MimeTypeTests.java
index bef9ebfde422..801794b1dfbd 100644
--- a/spring-core/src/test/java/org/springframework/util/MimeTypeTests.java
+++ b/spring-core/src/test/java/org/springframework/util/MimeTypeTests.java
@@ -539,6 +539,28 @@ void equalsIsCaseInsensitiveForCharsets() {
 		assertThat(m2.compareTo(m1)).isEqualTo(0);
 	}
 
+	@Test
+	void equalsIsCaseInsensitiveForParameterNames() {
+		MimeType m1 = new MimeType("text", "plain", singletonMap("Spring", "framework"));
+		MimeType m2 = new MimeType("text", "plain", singletonMap("spring", "framework"));
+		assertThat(m1).isEqualTo(m2);
+		assertThat(m2).isEqualTo(m1);
+		assertThat(m1).hasSameHashCodeAs(m2);
+		assertThat(m1.compareTo(m2)).isEqualTo(0);
+		assertThat(m2.compareTo(m1)).isEqualTo(0);
+	}
+
+	@Test
+	void equalsIsCaseInsensitiveForCharsetParameterName() {
+		MimeType m1 = new MimeType("text", "plain", singletonMap("Charset", "UTF-8"));
+		MimeType m2 = new MimeType("text", "plain", singletonMap("charset", "utf-8"));
+		assertThat(m1).isEqualTo(m2);
+		assertThat(m2).isEqualTo(m1);
+		assertThat(m1).hasSameHashCodeAs(m2);
+		assertThat(m1.compareTo(m2)).isEqualTo(0);
+		assertThat(m2.compareTo(m1)).isEqualTo(0);
+	}
+
 	@Test // gh-36729
 	void equalsIgnoresParameterValueQuoting() {
 		MimeType m1 = MimeTypeUtils.parseMimeType("text/plain; spring=\"framework\"");
diff --git a/spring-web/src/main/java/org/springframework/http/MediaType.java b/spring-web/src/main/java/org/springframework/http/MediaType.java
index b65e8053c944..72599932b634 100644
--- a/spring-web/src/main/java/org/springframework/http/MediaType.java
+++ b/spring-web/src/main/java/org/springframework/http/MediaType.java
@@ -503,7 +503,7 @@ public MediaType(MimeType mimeType) {
 	@Override
 	protected void checkParameters(String parameter, String value) {
 		super.checkParameters(parameter, value);
-		if (PARAM_QUALITY_FACTOR.equals(parameter)) {
+		if (PARAM_QUALITY_FACTOR.equalsIgnoreCase(parameter)) {
 			String unquotedValue = unquote(value);
 			double d = Double.parseDouble(unquotedValue);
 			Assert.isTrue(d >= 0D && d <= 1D,
@@ -651,7 +651,7 @@ public MediaType removeQualityValue() {
 			return this;
 		}
 		Map<String, String> params = new LinkedHashMap<>(getParameters());
-		params.remove(PARAM_QUALITY_FACTOR);
+		params.keySet().removeIf(PARAM_QUALITY_FACTOR::equalsIgnoreCase);
 		return new MediaType(this, params);
 	}
 
diff --git a/spring-web/src/test/java/org/springframework/http/MediaTypeTests.java b/spring-web/src/test/java/org/springframework/http/MediaTypeTests.java
index a7c9c090fb5a..6640b725a831 100644
--- a/spring-web/src/test/java/org/springframework/http/MediaTypeTests.java
+++ b/spring-web/src/test/java/org/springframework/http/MediaTypeTests.java
@@ -135,6 +135,12 @@ void parseMediaTypeIllegalQualityFactor() {
 				MediaType.parseMediaType("audio/basic;q=1.1"));
 	}
 
+	@Test
+	void parseMediaTypeIllegalQualityFactorWithUpperCaseParameterName() {
+		assertThatExceptionOfType(InvalidMediaTypeException.class).isThrownBy(() ->
+				MediaType.parseMediaType("audio/basic;Q=1.1"));
+	}
+
 	@Test
 	void parseMediaTypeIllegalCharset() {
 		assertThatExceptionOfType(InvalidMediaTypeException.class).isThrownBy(() ->
@@ -293,6 +299,18 @@ void isConcrete() {
 		assertThat(new MediaType("text", "*").isConcrete()).as("text/* concrete").isFalse();
 	}
 
+	@Test
+	void removeQualityValue() {
+		assertThat(MediaType.parseMediaType("audio/basic;q=0.8").removeQualityValue())
+				.isEqualTo(MediaType.parseMediaType("audio/basic"));
+	}
+
+	@Test
+	void removeQualityValueWithUpperCaseParameterName() {
+		assertThat(MediaType.parseMediaType("audio/basic;Q=0.8").removeQualityValue())
+				.isEqualTo(MediaType.parseMediaType("audio/basic"));
+	}
+
 	@Test  // gh-26127
 	void serialize() throws Exception {
 		MediaType original = new MediaType("text", "plain", StandardCharsets.UTF_8);